SOLUTION: A father and his son can do a job in 20 days. The father can do four times as much work as his son in a given amount of time. In how many days can the father do the job alone?

Question 696364: A father and his son can do a job in 20 days. The father can do four times as much work as his son in a given amount of time. In how many days can the father do the job alone?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A father and his son can do a job in 20 days.
The father can do four times as much work as his son in a given amount of time.
In how many days can the father do the job alone?
:
let d = time required by Dad working alone
then
4d = time required by sonny
:
let the completed job = 1
:
Each will do a fraction of the job, the two fractions add up to one.
:
+ = 1
multiply by 4d
4(20) + 20 = 4d
100 = 4d
d = 100/4
d = 25 days dad alone
:
:
Check this, son's time 4(25)
+
.8 + .2 = 1
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