Distance, rate, time question

Question

The OfficeJet printer can copy Janet's dissertation in 22 min. The LaserJet printer can copy the same document in 12 min. If the two machines work together, how long would they take to copy the dissertation?

Answer 1

So, Nicole, if I can do a job in 8 minutes, that means that every minute, 1/8 of the job gets done. No, that's not realistic, but it works for math problems.

 

1/22 + 1/12 = 1/t

 

What's the common denominator? 132x. Once we apply it, we don't need it and we just work with the denominators.

 

6t + 11t = 132

17t = 132

t = 7.76 = 7 munutes, 46 seconds

 

Hope this helps!