Х учеников, у скамеек. Тогда: (составляем два уравнения) 1. Уравнение для числа учеников. По два ученика на каждой скамейке и ещё семеро стоят, вместе получается общее число учеников. 2*х + 7 = у. 2. Уравнение для числа скамеек. Все ученики расселись по трое на скамейку, и ещё пять скамеек осталось. у / 3 + 5 = х 3. Решаем систему уравнений. Вместо "у" во втором уравнении записываем выражение из первого уравнения и приводим к общему знаменателю. Получаем: 2х + 7 + 15 = 3х. Решаем: х = 22 - это число скамеек. 4. Подставляем найденный результат в первое уравнение и получаем у = 2*22+7 = 51 - это число учеников.
By and large, the lake is part of the canal, called the Caledonian canal and which connects two sea-coast of Scotland. It is this peculiarity of the lake allows many researchers to argue that the legendary Loch Ness monster has the ability to migrate and not permanently located in a huge pond. There is even a version of that in the Loch ness comes not one, but several prehistoric animals to reproduce in the offspring. However, all opinions should be reviewed in detail, because some of them really deserve attention and are accepted by modern experts, as conclusive. According to geologists, the Loch ness appeared during the ice age, as a result of displacement of rocks: its length at the moment is about 37 kilometers, and its width more than half. Scottish pond, along with its medieval castle is one of the most visited places in Scotland: according to statistics, every year, to lake up more than half a million people from all corners of the globe
10х=5
х=2
2)5х+20-5-х-х-3
3х=12
х=4
3)4х+4-25-5х-5+4х-1
3х=-9
4)2х+4-20-5х-5+2х-3
-х=-24
х=24