Question

320-(b*4+120):5=40*6

Answer 1

320-(4b+120):5=240
-(4b+120):5=240-320
-(4b+120):5=-80
-(4b+120)=-80*5
-(4b+120)=-400 |*(-1)
(4b+120)=400
4b+120=400
4b=400-120
4b=280
$b= \frac{280}{4} = 70$