Working together, it takes two computers
12
minutes to send out a company’s email. If it takes the slower computer
30
minutes to do the job on its own, how long will it take the faster computer to do the job on its own?

Question

Working together, it takes two computers 
12
 minutes to send out a company’s email. If it takes the slower computer 
30
 minutes to do the job on its own, how long will it take the faster computer to do the job on its own?

anonymous · Answer

Let x = time (minutes) it takes for the faster computer to do the job alone
then
12(1/30 + 1/x) = 1

anonymous · Answer

multiplying both sides by 30x:
12(x + 30) = 30x
12x + 360 = 30x
360 = 18x
20 minutes = x

anonymous · Answer

Did that help? :3