(9*y-30):9=50 (350:b+10)*7=560
(9у-30)÷9=50 9у-30=50×9 9у-30=450 9у=450+30 9у=480 у=480÷9 у=53 3/9 у=53 1/3 (350÷b+10)×7=560 350÷b+10=560÷7 350÷b+10=80 350÷b=80-10 350÷b=70 b=350÷70 b=5