X+320=80×7
X+320=560
X=560-320
Х=240
X-180=240:3
X-180=80
X=80+180
Х=260
400-x=275+25
-x=275+25-400
-x=-100
х=100
X+320=80×7
X+320=560
X=560-320
Х=240
X-180=240:3
X-180=80
X=80+180
Х=260
400-x=275+25
-x=275+25-400
-x=-100
х=100