SOLUTION: Fred can paint a certain room in 5 hours. One day Fred decides to help his friend Jack paint such a room. After they work together for 2 hours Fred goes home and leaves Jack to fin

Question 579917: Fred can paint a certain room in 5 hours. One day Fred decides to help his friend Jack paint such a room. After they work together for 2 hours Fred goes home and leaves Jack to finish painting the room. Jack requires 4 more hours to finish the room. How long would it have taken Jack to paint the room alone?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Fred can paint a certain room in 5 hours.
One day Fred decides to help his friend Jack paint such a room.
After they work together for 2 hours Fred goes home and leaves Jack to finish painting the room.
Jack requires 4 more hours to finish the room.
How long would it have taken Jack to paint the room alone?
:
Let j = time required by jack to paint the room alone
let the completed job = 1; (a painted room)
:
From the information given, we know Jack painted for a total of 6 hrs and Fred 2 hrs
:
+ = 1
multiply by 5j
5j* + 5j* = 5j
cancel the denominators
2j + 5(6) = 5j
30 = 5j - 2j
30 = 3j
j =
j = 10 hrs for jack to do it alone
;
:
Check this
+ =
.4 + .6 = 1
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