Two cyclists, A and B, are 145 miles apart on a straight roa

[BTGmoderatorDC]

Two cyclists, A and B, are 145 miles apart on a straight road. At 1:30 p.m., cyclist A begins riding at a constant speed of 20 miles per hour toward cyclist B. At 2:00 p.m., cyclist B begins riding toward cyclist A at a constant speed. At 5:00 p.m. they meet. How fast, in miles per hour, was cyclist B riding?

A. 20
B. 25
C. 30
D. 35
E. 40

OA B

Source: Princeton Review

[Ian Stewart]

In the first half hour, A covers 10 miles. So at 2pm, the cyclists are 135 miles apart. Together they will cover this distance in 3 hours, since they meet at 5pm. Since A covers 60 miles in that time, B must cover the rest, or 75 miles, and so B's speed must be 25 mph.