.
Let x be the average speed of the trip TO the lake, in miles per hour.
Then the average speed on the returning trip was (x-20) mph.
The distance to the lake is 2*x miles; the distance from the lake to the home was 3*(x-20).
Both distances are the same, which gives you an equation
2x = 3*(x-20).
Simplify and solve for x
2x = 3x - 60
60 = 3x - 2x
x = 60.
ANSWER. Sarawong's average speed on the outbound trip was 60 mph.
CHECK. The distance to the lake was 2*60 = 120 miles.
The distance back was 3*(60-20) = 3*40 = 120 miles.
Both distances are the same ----> hence, the solution is correct.
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For introductory lessons on Travel and Distance problems, see
- Travel and Distance problems
- Travel and Distance problems for two bodies moving in opposite directions
- Travel and Distance problems for two bodies moving in the same direction (catching up)
They are written specially for you.
You will find the solutions of many similar problems there.
Read them and learn once and for all from these lessons on how to solve simple Travel and Distance problems.
Become an expert in this area.
