Distribute 3 into the parenthesis = 6d-24
Distribute -18 into (d-3) = -18d+54
Then you’ll have: 6d-24=11d-18d+54
Combine Like terms: 6d-24=-7d+54
Move the variables to one side and the constants to the other side: 6d+7d=54+24
Solve for d: 13d=78
d=6