1/4у + 4 = 16 - 1/12у
3/12y + 4 = 16 - 1/12y
3/12y + 1/12y + 4 = 16
3/12y + 1/12y = 16 - 4
4/12y = 12
1/3y = 12
y = 12 * 3
y = 36
Удачи)