3(2y+6) - 4(y-2) = 20
We are given to solve:
$\displaystyle 3(2y+6)-4(y-2)=20$
Distribute the coefficients in front of the parentheses:
$\displaystyle 6y+18-4y+8=20$
Now collect like terms on the left. Can you finish?
No. We have:
$\displaystyle 6y+18-4y+8=20$
Group like terms together:
$\displaystyle (6y-4y)+(18+8)=20$
Now combine the like terms:
$\displaystyle 2y+26=20$
All terms are divisible by 2, so divide every term by 2:
$\displaystyle y+13=10$
Subtract 13 from both sides:
$\displaystyle y=-3$