I assume that you want to solve for d:

......... get rid of the denominator by multiplying by (5 - 3d):

......... expand the bracket:

......... collect all terms containing d at the RHS, the other at the LHS:

......... factor out d:

......... divide both sides by the bracket:

......... that's it!

I've done this problem extensively so that you have an example to do all similar questions.