Answer:
w = 5
3 x 5 = 15
3 x w will mean multiplication so you always want to do the opposite. First you want to get rid of known numbers such as the 3, to do that you will need to divide 3 from both sides! (As I had said use the opposite of the operations shown). 3 from 3 is obviously going to be 0 because your getting rid of the three, and 15 divided by 3 is 5! So therefore, you will be left with w = 5.