A and B ran, at their respective constant rates, a race of 480 m. In the first heat, A gives B a head start of 48 m and beats him by 1/10th of a minute. In the second heat, A gives B a head start of 144 m and is beaten by 1/30th of a minute. What is B’s speed in m/s?
Choose the correct choice from the following choices:
A) 12
B) 14
C) 16
D) 18
E) 20
Let x be the speed of B.   Write the equation:   (480-48)/x (time of B for first heat) - 6 (seconds, time B lost to 12 first heat) = TIME OF 12 (in both heats 12 runs with constant rate, so the time for first and second heats are the same)=(480-144)/x (time of B for second heat) + 2 (seconds, time B won to 12 second heat)   (480-48)/x-6=(480-144)/x+2   x=12   12nswer: 12.
<result>A</result>
A and B ran, at their respective constant rates, a race of 480 m. In the first heat, A gives B a head start of 48 m and beats him by 1/10th of a minute. In the second heat, A gives B a head start of 144 m and is beaten by 1/30th of a minute. What is B’s speed in m/s?