Bill likes long bike rides. On one ride, he goes biking for seven hours. For the first hour, he bikes
at a speed of 16 miles per hour. For the next two hours, he bikes at a speed of 12 miles per
hour. He remembers biking 112 miles over the seven hours. Compute the average speed, in miles
per hour, Bill biked during the last four hours of his trip.  Choose the correct choice from the following.
A) 18	B) 14	C) 22	D) 27	E) 35
He has to travel 112 - 16 - 12 * 2= 
<gadget id="calculator">112 - 16 - 12 * 2</gadget>
<output>72</output>
72 miles in 4 hours   72 / 4= 
<gadget id="calculator">72 / 4</gadget>
<output>18</output>
18 miles per hour   correct answer 18
<result>A</result>
Bill likes long bike rides. On one ride, he goes biking for seven hours. For the first hour, he bikes
at a speed of 16 miles per hour. For the next two hours, he bikes at a speed of 12 miles per
hour. He remembers biking 112 miles over the seven hours. Compute the average speed, in miles
per hour, Bill biked during the last four hours of his trip.