540÷(17-х)=60
17-х=540÷60
17-х=9
х=17-9
х=8
540÷(17-8)=60
540÷9=60
60=60
t×7-80=340
t×7=340+80
t×7=420
t=420÷7
t=60
(8×y-30)÷9=50
8×y-30=50×9
8×y-30=450
8×y=450+30
8×y=480
y=480÷8
y=60
(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