It deals with proportions. You put hotdogs over minutes. Like 10 hotdogs over 4 minutes because that's how long it took to eat those hotdogs. Then put 18 minutes on the bottom of the next fraction. Then you cross multiply. 10 x 18 which equals 180. Then you divide. 180/4 Which equals 45 hotdogs. He ate 45 hotdogs in 18 minutes. 10 hotdogs in 4 minutes 45 hotdogs in 18 minutes.