45+(71-b*9)=80 решите плиз

45+(71-b*9)=80
71-9ь=80-45
71-9ь=35
9ь=71-35
9ь=36
ь=36:9
ь=4

45+(71b*9)=8071-9b=80-45
71-9b=35
9b=71-35
9b=36
b=36:9
b=4