A serving dish consists of three cylinders. Each cylinder has a diameter of 6 inches and a height 4 inches. What is the volume of the serving dish?

Easiest ways to solve them are to take the denominator and numerator and and divide the one you are asked to use to answer and divide and see if it works on both. 
  Example: first     105 / 15 = 7 )  Then: 105 / 7 = 15
                             119              )             119 / 7 = 17

Hope I helped. :D