Question

15 (y-4)-2 (y-9)+5 (y+6)=0

Answer 1

15y-60-2y+18+5y+30=0
15y-2y+5y=60-18-30
18y=12
y=1.5

Answer 2

15(y-4)-2(y-9)+5(y+6)=0
18y-12=0

Add 12 to both sides
18y-12+12=0+12

Refine
18y=12

Divide both sides by 18

18y=12
18     18

Refine
y=2/3