Question 739723
Remember distance problems?  The formula is Distance = rate x time.  Work problems have a similar formula:  Work = rate x time.  Work is often 1 as in 1 complete job.<P>
The groundskeeper's rate is 1=r*40 so r = 1/40 of the job per minute. The assistant works at a rate of 1/55 of the job per minute (1 = r*55 so r=1/55).<P>
To find the time when they work together, use the equation with their combined rate: 1/40 + 1/55 = 19/440<P>
1 = 19/440 * t so t = 440/19 = 23 and 3/19 minutes or 23 minutes 9.47 seconds.
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