It takes printer A 4 more minutes than printer B to print 40 pages. Working together, the two printers can print 50 pages in 6 minutes. How long will it take printer A to print 80 pages?
* 12
* 18
* 20
* 24
* 30










When we have two things working together, we can add their rates:
[40 / (x + 4)] + (40 / x) = (50 / 6)
Solving this, you get x = 8 (we can rule out -2.5)
So it takes printer A 12 minutes to print 40 pages, it will take it 24 minutes to print 80 pages. The answer is (D).