Question 1195305
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Here is a very different way to solve "working together" problems like this.<br>
Consider a convenient common multiple of the two given times for the two workers working alone.  For this problem, 15 hours is a nice choice: 1.5*10 = 15; 2.5*6 = 15.<br>
In 15 hours, Brown could do the whole job 15/1.5 = 10 times; in 15 hours his son could do the whole job 15/2.5 = 6 times.
So together in 15 hours the two could do the whole job 10+6 = 16 times.
So to do the single whole job once would take them 15/16 hours.<br>
ANSWER: 15/16 hours<br>