Aaron starts walking at a rate of 3 mi/h on a road toward a store 10 mi away. Zhang leaves the store when Aaron starts walking, and he walks toward Aaron along the same road at 2 mi/h. How many hours will pass before they meet?
A. 1.5 h
B. 10 h
C. 2 h
D. 3 h
C. 2 hours
Aaron will have already walked 6 miles when Zhang leaves the store. When Zhang starts walking, the remaining distance between them is 4 miles. They are both walking towards each other at a combined rate of 3 mi/h + 2 mi/h = 5 mi/h. Therefore, it will take them 4 miles / 5 mi/h = 0.8 hours to meet. Added to the initial 1.2 hours it took Aaron to walk 6 miles, the total time before they meet is 1.2 hours + 0.8 hours = 2 hours.