7х+2х=3,528
9х=3,528
х=3,528:9
х=0,392
Проверка
7*0,392+2*0,392=3,528
7*0,392=2,744
2*0,392=0,784
2,744+0,784=3,528
3,528=3,528
X - 24 = 300 : 3 * 45 + 123
x - 24 = 100 * 45 + 123
x - 24 = 4500 + 123
x = 4623 + 24
x = 4647
Проверка
4647 - 24 = 300 : 3 * 45 + 123
4623 = 100 * 45 + 123
4623 = 4500 + 123
4623 = 4623
(72-(23х2)):2=13см-ширина
13х23=299см^2
Ответ:299см^2