Question 692265
Let x=the amount of time it takes the carpenter working alone to put up the cover
Then the carpenter works at the rate of 1/x of the cover per hour
The carpenter and his partner works at the rate of 1/(3 3/7)=1/(24/7)=7/24 of the cover per hour
The partner works at the rate of 1/8 of the cover per hour, soooo

1/x + 1/8 =7/24  multiply each term by 24x
24+3x=7x
4x=24
x=6 hours time it takes the carpenter working alone

CK
1/6+1/8=7/24
4/24+3/24=7/24
7/24=7/24

Hope this helps---ptaylor