Steps to solve:
3(6d - 24) = 6(12 + 3d)
~Distribute
18d - 72 = 72 + 18d
~Subtract 18d to both sides
18d - 72 - 18d = 72 + 18d - 18d
~Simplify
-72 = 72
~Subtract 72 to both sides
-72 - 72 = 72 - 72
~Simplify
-144 = 0
Their are no real solutions.
Best of Luck!