SOLUTION: Doy and his son can do a job in 4 1/2 days, After they have worked for 3 days, Doy got sick and the son finished the task in 6 more days. How many days each required to do the enti

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Doy and his son can do a job in 4 1/2 days, After they have worked for 3 days, Doy got sick and the son finished the task in 6 more days. How many days each required to do the enti      Log On


   



Question 492733: Doy and his son can do a job in 4 1/2 days, After they have worked for 3 days, Doy got sick and the son finished the task in 6 more days. How many days each required to do the entire task?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Doy and his son can do a job in 4 1/2 days,
After they have worked for 3 days, Doy got sick and the son finished the task in 6 more days.
How many days each required to do the entire task?
:
Let d = D's working time alone to do the job
Let s = son's working time to do it
Let the completed job = 1
:
"Doy and his son can do a job in 4 1/2 days," therefore
4.5%2Fd + 4.5%2Fs = 1
:
From the given information, we know that the son worked a total 9 days
:
3%2Fd + 9%2Fs = 1
:
Multiply the 1st equation by 2, use elimination here
9%2Fd + 9%2Fs = 2
3%2Fd + 9%2Fs = 1
----------------------------subtraction eliminates s find d
6%2Fd = 1
multiply both sides by d
d = 6 days for D to do the job alone
:
Find s
3%2F6 + 9%2Fs = 1
multiply by 6s, results:
3s + 6(9) = 6s
54 = 6s - 3s
54 = 3s
s = 54%2F3
s = 18 days for the son to do the job alone
:
:
We can check these solutions in the 1st equation
4.5%2F6 + 4.5%2F18 =
.75 + .25 = 1