He runs for 3 hours because 2 x 1.5 = 3. He runs for 180 minutes because 3 x 60 = 180. He runs 15 miles because 180 / 12 = 15.
This justifies what answer for what question? Q & A:
While Paul watches movies, he runs on his treadmill. He can run a mile in 12 minutes. He watches two movies, which are an average length of 1.5 hours. How many miles does he run?
15