Since all three equations are equal, you take 15 x 20, which =300, once again because all of the equations are equal, take 300 and divide it by 5, that will give you your first question mark.{you should have gotten 60.} To find the second one, you are going to apply the same concept, Take 300 and divide it by 6, giving you your second question mark. {you should have gotten 50}...
P.S.: {hope I helped} :)