Two trains are traveling on parallel tracks in the same direction. The faster train travels at 150 miles per hour, while the slower train travels at 100 miles per hour. At 2 o’clock the faster train is 10 miles behind the slower one. How far apart are the two trains at 5 o'clock?  Choose the correct choice:
A) 60 miles
B) 80 miles
C) 90 miles
D) 140 miles
E) 400 miles
Answer = D. 140 miles   Relational speed = 150 - 100= 
<gadget id="calculator">150 - 100</gadget>
<output>50</output>
50 miles per hour   In 3 hours, difference= 50 * 3= 
<gadget id="calculator">50 * 3</gadget>
<output>150</output>
150 miles   Fast train trailing 10 miles, so effective difference= 150 - 10= 
<gadget id="calculator">150 - 10</gadget>
<output>140</output>
140 miles
<result>D</result>
Two trains are traveling on parallel tracks in the same direction. The faster train travels at 150 miles per hour, while the slower train travels at 100 miles per hour. At 2 o’clock the faster train is 10 miles behind the slower one. How far apart are the two trains at 5 o'clock?