For problems like these I take the largest number in this case 10, and start writing out what 2 numbers would give me 10. 0+10, 1+9, 2+8, 3+7...while doing that I subtract the numbers as well. thus 3+7=10 3-7=-4
a. 50 miles x 2 hours = 100 miles b. 50 miles x 4.3 hours = 215 miles c. Converting minutes to hours, it would make 20 minutes become 0.333 hours. 50 x 0.333 = 16.65 miles