a-80=320+350 590-X=110+260
a-80=670 590-X=370
a=670+80 X=590-370
a=750 X=220
750-80=320+350 590-220=110+260
670=670 370=370 X+120=900-540 480+b=960-150
X+120=360 480+b=810
X=360-120 b=810-480
X=240 b=330
240+120=900-540480+330=960-150
360=360 810=810