Lizzy: The number of math problems that Marvin practiced today is three times as many as the number of problems he solved yesterday. His friend, Arvin, has practiced twice as many math problems on each day. How many math problems have they practiced altogether if Marvin solved 40 math problems yesterday?.
Me: Hmmm, let me think. I think this is the detailed solution:
If Marvin solved 40 math problems yesterday, he has solved 40 * 3 = 120 math problems today. The total number of math problems that Marvin has practiced is 120 + 40 = 160. Arvin has practiced twice as many as Marvin, so has practiced 160 * 2 = 320 problems. Together, Marvin and Arvin have solved 320 + 160 = 480 math problems. Final answer: 480.