Two trains leave the same train station at 6:00 am and 6:45 am and they travel at 100 kph and 120 kph respectively. How many kilometers from the train station will the two trains be together? Choose the correct choice from the following answers.
A) 420
B) 450
C) 480
D) 510
E) 540
At 6:45, the first train is 75 km ahead.   The second train gains 20 km each hour.   The time it takes the second train to catch the first train is 75 /20= 
<gadget id="calculator">75 /20</gadget>
<output>15/4 = around 3.75</output>
3.75 hours.   In this time, the second train travels   3.75*120= 
<gadget id="calculator">  3.75*120</gadget>
<output>450</output>
450 km.   The answer is 450.
<result>B</result>
Two trains leave the same train station at 6:00 am and 6:45 am and they travel at 100 kph and 120 kph respectively. How many kilometers from the train station will the two trains be together?