2/15y + 3/4 = 5/6
2/15y + 3/4 -5/6=0
(2*4+3*15y-5*10y)/60=0
8+45y-50y=0
-5y=-8
y=8/5
y=15
2)
5/8m - 7/12m + 5/6m = 1/4
(5*3-7*2+5*4)m=1/4
(15-14+20)m=1/4
21m=1/4
m=1/4:21
m=1/81
3)2 1/5 - 3/4m = 59/60
11/5 - 3/4m = 59/60
- 3/4m = 59/60-5/8
3/4m=(59*2-5*15)/120
3/4m=(118-75)120
3/4m=43/120
m=43/120:3/4
m=43/120*4/3
m=43/90