Question 1150249
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Here is an alternative to the standard algebraic method for solving "working together" problems like this, as shown by the other tutor.<br>
Consider the least common multiple of the two given times.  One computer can do the job in 30 hours; the other in 12 hours.<br>
The LCM of 30 and 12 is 60.  In 60 hours, the first computer could do the job 60/30 = 2 times; the other could do it 60/12 = 5 times.<br>
So in 60 hours the two computers together could do the job 7 times; that means the amount of time it takes them to do the one job is 60/7 hours.<br>
And for a student competing in timed math competitions, where only an answer is needed, without any formal solution method, the answer to any question like this involving two workers working together is (a*b)/(a+b), where a and be are the amounts of time required for the two workers individually.<br>
In this problem, that is<br>
{{{(12*5)/(12+5) = 60/7}}}<br>