SOLUTION: Ron and Landon are digging for the footer for a building. Ron can do the job alone in 20 hours. Landon can do the job alone in 30 hours. How long will it take both of them working

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Question 1159715: Ron and Landon are digging for the footer for a building. Ron can do the job alone in 20 hours. Landon can do the job alone in 30 hours. How long will it take both of them working together to do the job?
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39620) About Me  (Show Source):
Answer by greenestamps(13203) About Me  (Show Source):
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An alternative to the standard algebraic method for solving this kind of problem....

Consider the least common multiple of the two times, which is 60 hours.

In 60 hours, Ron could do this job 60/20=3 times and Landon could do it 60/30=2 times.

So in 60 hours the two together could do the job 3+2=5 times.

So the amount of time it would take them together to do the one job is 60/5 = 12 hours.