Question 731547
 Mr. Johnson paints 5/9 of his house in 10 hours, and then is joined on the job by his neighbor, Mr. Prima.
 Together, they finish painting the house in 3 hours.
 How long would it have taken Mr. Prima to do the entire job himself?
:
Find how many hrs for Johnson to do the house alone
{{{5/9}}}h = 10
h = 10*{{{9/5}}}
h = 18 hrs
:
Let p = time for Prima to do it alone
Let the completed job = 1
J worked 13 hrs, P worked 3 hrs
{{{13/18}}} + {{{3/p}}} = 1
Multiply by 18p, resulting in
13p + 18(3) = 18p
54 = 18p - 13p
54 = 5p
p = 54/5
p = 10.8 hrs