David can type a 50-page paper in 8 hours. Last month David and Andy together typed a 50-page paper in 6 hours. How long would Andy take to type a 50-page paper by himself?

1 Answer
Apr 14, 2016

#24# hours

Explanation:

Typing #50# pages in #8# hours means that David types #50/8# pages per hours #=25/4# pages per hour. In six hours he would have typed #25/4 * 6 = 75/2# pages.

Therefore Andy typed #50 - 75/2# pages which is #(100-75)/2 = 25/2# pages.

#25/2# pages in #6# hours means that Andy types at #25/(2*6)# pages per hour, which is #25/12# pages per hour.

#50/(25/12) = 50*12/25 = 24# hours to type 50 pges.