x+320=80-7
x+320=560
x=560-320
x=240
Проверка: 240+320-560
x-180=240:3
x-180=80
x=80+180
x=260
260-180=80
400-x=275+25
400-X=300
x=400-300
x=100
400-100=300
x+320=80-7
x+320=560
x=560-320
x=240
Проверка: 240+320-560
x-180=240:3
x-180=80
x=80+180
x=260
260-180=80
400-x=275+25
400-X=300
x=400-300
x=100
400-100=300