Question 80456
If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?
:
Let t = time required to complete the job together
:
Let the completed job = 1
:
A simple equation:
{{{t/4}}} + {{{t/6}}} = 1
:
Multiply equation by 12 to get rid of the denominators, you then have:
3t + 2t = 12
:
5t = 12
:
t = 12/5
:
t = 2.4 hrs working together
:
:
Check solution of t = 2.4:
2.4/4 + 2.4/6 =
 .6  +  .4 = 1