Question 454216
After one hour Carl painted 1/8 of the house leaving 7/8 to paint

3/8+3/x=7/8
3/x=4/8
4x=24
x=6
Bill can do it in 6 hours
or 
1/8+3/8+3/x=1
4/8+3/x=1
3/x=4/8
4x=24
x=6
Bill can do it in 6 hours alone