Marcus can walk 1 mile to the library in about the same time he can bicycle 2.5 miles to the sporting good store. His speed on the bicycle is 6 mi/h faster than his walking speed What is Marcus's walking speed?

Answer: Marcus's walking speed is 4 mph

Step-by-step explanation:

Let x represent Marcus's walking speed.

His speed on the bicycle is 6 mi/h faster than his walking speed. This means that his speed on the bicycle would be

x + 6

Time = distance/speed

Time spent by Marcus in walking 1 mile to the library is

1/x

Time spent by Marcus in bicycling 2.5 miles to the sporting good store is

2.5 / (x + 6)

Since the time that he spends in walking to the library is about the same time that he spends in bicycling to the sporting good store, then

1/x = 2.5 / (x + 6)

Cross multiplying, it becomes

1 * (x + 6) = 2.5 * x

x + 6 = 2.5x

2.5x - x = 6

1.5x = 6

x = 6/1.5 = 4