Question 259068
The OfficeJet Printer can copy Maria's document in 8 minutes.
 The LaserJet printer can copy the same document in 12 minutes.
 If the two machines work together, how long would it take to copy the document?
:
Let t = time required when both machines work together
Let the complete job = 1; (copying the document)
:
A typical shared work equation:
{{{t/8}}} + {{{t/12}}} = 1
Clear the denominators, multiply by 24, results:
3t + 2t = 24(1)
5t = 24
t = {{{24/5}}}
t = 4.8 min or  4 min + .8(60) = 48 seconds
;
:
Check solution
4.8/8 + 4.8/12 = 
.6 + .4 = 1