Question 1118392
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The trail is 15 miles long, and he rode the whole trail one way and then back.  Using what you show "x" and "x+2" for the speeds on the two parts, the total time (distance divided by rate) is<br>
{{{15/(x+2)+15/x}}}<br>
The question asks for AN expression for the total travel time; so there is no need to simplify that expression.<br>
If his average speed for the first half was 12mph, then his average for the second half was 10mph; the total time in hours is then<br>
{{{15/12 + 15/10 = 5/4 + 3/2 = 11/4}}}<br>
The total travel time was 11/4 hours, or 2 3/4 hours, or 2 hours 45 minutes.