Question 1094895
 You can paint the house in 10 hours
 jeff can paint it in 12 and 
 andy can paint it in 18. 
You work the entire time but Jeff ended up taking an hour break and Andy took a 2-hour break.
 If you started painting at 8 am what time did you finish?
:
let t = no. of hrs from 8 Am to complete the job
then
(t-1) = painting time of Jeff
and
(t-2) = painting time of Andy
:
let the completed job = 1
:
Each will do a fraction of the job, the 3 fractions add up to 1
{{{t/10}}} + {{{((t-1))/12}}} + {{{((t-2))/18}}} = 1 
multiply by the least common multiple 180, then cancel the denominators
18t + 15(t-1) + 10(t-2) = 180
18t + 15t - 15 + 10t - 20 = 180
18t + 15t + 10t = 180 + 15 + 20
43t = 215
t = 215/43
t = 5 hrs, 8:00 + 5:00 = 13:00 or 1 pm they finish