Уравнения идут по столбцам.
Первый
1.
5x = 25
x = 25 : 5
x = 5
2.
-3x = 9
-x = 9 : 3
-x = 3
x = -3
3.
3x = - 15
x = -15 : 3
x = -5
4.
-3x = -27
x = -27 : (-3)
x = 9
5.
4x = 12
x = 12 : 4
x = 3
Второй
1.
5x + 10 = 25
5x = 25 - 10
5x = 15
x= 3
2.
4x + 1 = 13
4x = 13 - 1
4x = 12
x = 3
3.
3x - 4 = 8
3x = 8 + 4
3x = 12
x = 4
4.
6x - 2 = 16
6x = 16 + 2
6x = 18
x = 3
5.
7x + 3 = 17
7x = 17 - 3
7x = 14
x = 2
Третий
1.
7x = 41 - 4x
7x + 4x = 41
11 x = 41
x = 3 8/11
2.
4x = 2x - 9
4x - 2x = -9
2x = -9
x = - 4.5
3.
2x = x - 18
2x - x = -18
x = -18
4.
2x = 6x + 16
2x - 6x = 16
-4x = 16
-x = 4
x = -4
5.
12x = x + 24
12x - x = 24
11x = 24
x = 2 2/11
Четвёртый
1.
8x + 9 = 2x - 80
8x - 2x = - 80 - 9
6x = - 89
x = - 14 5/6
2.
3 - 5x = 40 - 7x
-5x + 7x = 40 - 3
2x = 37
x = 18.5
3.
11 - 3x = x + 15
-3x - x = 15 - 11
-4x = 4
x = -1
5.
6x - 8 = 3x - 4
6x - 3x = -4 + 8
3x = 4
x = 1 1/3
Пятый
1.
2(x - 4) = 15 - x
2x - 8 = 15 - x
2x - x = 15 + 8
x = 23
2.
3(1 - 9x) = 13 - x
3 - 27x = 13 - x
- 28x = 10
x = - 5 / 14
3.
4(2x - 13) = 5 + x
8x - 52 = 5 + x
7x = 57
x = 8 1/7
4.
17 - 4x = 5(x - 7)
17 - 4x = 5x - 35
-9x = -52
x = 9 7/9
5.
6(x - 4) = 5(2 - 3x)
6x - 24 = 10 - 15x
21x = 34
x = 1 13/21
90 грамм соли было в растворе первоначально.
Объяснение:
1)80-40=40% - 90г соли