Answer:
It will take him 15 days before all of the math problems finish.
Explanation:
8 ÷ 3 = 0.266666667
8 math problem ÷ 30 minutes = math problems per minutes
0.266666667 X 45 = 12
math problems per minute X 45 Minutes = math problems per day
175 ÷ 12 = 14.5833333
math problems per day ÷ math problem = days