Think Order of Operations, PEMDAS, parentheses, exponents, multiply and divide, add and subtract.
First you have to distribute the 5 on the left side and the 9 on the left side to each term in the corresponding parentheses.
5*2z-5*3 = 9*z-9*3
10z-15 = 9z-27
then add 15 to both sides
then subtract 9z from both sides
that's your answer! Just go through the order of operations and remember whatever you do to one side of the equation you must do to the other.