Объяснение:
WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.WRITING Choose ONE of the topics and write. Topic 1: You are a charitable volunteer in your city and always give a hand to those who are in need: clean the apartments of the disabled people; bring food to animal refuges to feed homeless animals; organise campaigns to raise money and collect toys and clothes for the local orphanages. Your new idea is to write a formal letter to the local mayor to ask him/her for any help he/she can provide to help your charity organisation. Include in your letter the following information: • The title of your charity organisation: • What you have done/are doing aiready; • How you would like the mayor to help your charity organisation. Use appropriate style and examples in your letter.
Объяснение: 
это первый шаг теперь второй 
теперь из первого уравнения xy=1 подставим во второе 3*1+2y²=1 => y²=-1 что не может быть остальные случаи я тоже рассмотрел там выходит тоже самое а значит нет решений ; 4) здесь же можно сразу собрать в формулу 
рассмотрим вторую систему и случаи при которых равенство верное их всего 2 а остальные два не подходят тогда в первом 1) x-y-2=1 x-y=3 подходит так как x-y=3 ; x-y=3 2) x-y-2=-3 x-y=-1 что тоже подходит теперь их нужно проверить подставим в первую систему x-y=3 => x=y+3 мы получим 
тогда первое решение (-1;-4) второе (6;3) теперь рассмотрим второй случай когда x=y+1 подставим и решим 
получим третье решение (5;4) и четвертое (-2;-3) пятое задание на фото
1) - 8 * (-3) = 24
2) 12 : (-3) = - 4
3) 24 + (- 4) = 20
4) - 120 : 20 = - 6
5) - 48 : (- 16) = 3
5) - 6 - 3 = - 9
- 75 * 4 - 204 : (- 3) + (- 210) : (- 7) = - 202
1) - 75 * 4 = - 300
2) 204 : (- 3) = - 68
3) - 210 : (- 7) = 30
4) - 300 - (- 68) = - 300 + 68 = - 232
5) - 232 + 30 = - 202
- 20,25 : (- 3,6) + 90,72 : (- 4,5) - 7,5 * 3,2 = - 38,535
1) - 20,25 : (- 3,6) = 5,625
2) 90,72 : (- 4,5) = - 20,16
3) 7,5 * 3,2 = 24
4) 5,625 + (- 20,16) = 5,625 - 20,16 = - 14,535
5) - 14,535 - 24 = - 38,535
Задача. Пусть х - цена ткани до подорожания. Процент - это сотая часть числа: 20% = 0,2; 25% = 0,25.
1) х * 0,2 + х = 1,2х - цена ткани после повышения цены на 20%;
2) 1,2х * 0,25 + 1,2х = 1,5х - цена ткани после повышения новой цены на 25%
3) Пропорция: 1 - 100% (первоначальная цена)
1,5 - х (окончательная цена)
х = 1,5 * 100 : 1 = 150%
150% - 100% = 50% - на столько процентов была повышена первоначальная цена.