Question 1030169
Let x=amount of time it takes working together for them to complete a total of 8 jobs
Uncle Donald works at the rate of 2/3 of the job per day
Cousin Kelly works at the rate of 4/7 of the job per day
In three days, Cousin Kelly did (4/7)*3=12/7 of the jobs, leaving (8=56/7)
(56/7 - 12/7)=44/7 of the jobs yet to be completed

Working together, they work at the rate of (2/3)+(4/7)=(14/21)+(12/21)=26/21 of the jobs per day
Soooooo  our equation to solve is:
(26/21)*x=44/7  multiply each side by 21 to get rid of fractions
26x=132
x=5.08 days

hope this helps----ptaylor