For each catch up or meeting questions; I've found that relative speed concept is very useful!

1. When

catching up, the relative speed is the

difference between rate A vs rate B = which is 58 mph - 50 mph = 8 mph.

2.

First, we want to to know when the A catch up the B :

- Rate : 8 mph

- Distance : 20 miles (since 20 miles is the difference)

- So, we can calculate Time = \(\frac{Distance}{Rate}\) = \(\frac{20}{8}\) = 2,5 hrs.

3.

Second, since we must calculate when A is 8 miles ahead, so we must calculate how much time A will set this difference.

- Rate : 8 mph

- Distance : 8 miles (we want to set 8 miles difference)

- Time = \(\frac{Distance}{Rate}\) =\(\frac{8}{8}\)= 1 hour

4. The sum of number (2) and (3) is the answer = 3,5 hrs. Hence E.

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