x+320=80×7 x-180=240:3 400-x=275+25

1)x+320=80×7 x=80×7 x=560-320 x=240240+320=80×72)x-180=240:3 x=240:3 x=80+180 x=240240-180=240:33)400-x=275+25 x=275+25 x=400-300 x=100 400-100=275+25