To solve for d, the first step is to combine all like terms and try to get d isolated on one side of the equals sign. The only like terms that we can see are d and 3d — but that's it. So, we can subtract d from both sides to end up with 5c = 2d - 1. Because we want to isolate d, now we must add 1 to both sides to get 5c + 1 = 2d. But this isn't our answer, because there is still a coefficient attached to d. Therefore we must divide both sides by 2 to receive a final answer of [tex]\frac{5c-1}{2}=d[/tex].