Ответ:

4-9/2y=2y-16/3y+20/3

16/3y-9/2y-2y=20/3-4

32/6y-27/6y-12/6y=40/6-24/6

-7/6y=16/6. y=16/6×6/7=16/7

3-1/3(2/3y+1/2)=1/3y+1,5

3-2/9y-1/6=1/3y+1,5

1/9y=17/6-15/10

1/9y=40/30

y=40/30×9=12