For number 3, the answer is B because I use this equation which is 60/1, 120/2, 180/3, so I know that y=60x. For number 4, I know that the rate is 60 miles per hour, so I just take 450 divided 60 to get how long does it take to travel 450 miles which equal 7.5 hours which is A. For number 5, I know that 6 3/4 hours will equal 6.75 hours, so now I just need to take 60 times 6.75 hours to get how many miles does the train ride in 6.75 hours which equal 405 miles which is C. Hope it help!
. Filling in accordingly, 
. This simplifies to 
and 36=6x. Therefore, x = 6 so the bases are 6 and 12.