A car averages 55 mph for the first 4 hours of a trip and averages 70 mph for each additional hour. The average speed for the entire trip was 60 mph. How many hours long is the trip?
Answers.
A) 6
B) 8
C) 11
D) 12
E) 14
In 4hr journey = 55*4= 
<gadget id="calculator">55*4</gadget>
<output>220</output>
220mph   Let in the next additional hour journey= 70*x =70x mph   So, (220+70x)/(4+x)= 60   =&gt; 220+70x = 240+60x   =&gt; 10x = 20   =&gt; x = 2h   So the trip is (4+x)=&gt; 6 hours long   6NSWER:6
<result>A</result>
A car averages 55 mph for the first 4 hours of a trip and averages 70 mph for each additional hour. The average speed for the entire trip was 60 mph. How many hours long is the trip?