SOLUTION: Mark and Bert together can finish the job in 4 hours. How fast can Bert finish the job alone if Mark can finish it in 9 hours?

Question 253758: Mark and Bert together can finish the job in 4 hours. How fast can Bert finish the job alone if Mark can finish it in 9 hours?
Answer by ptaylor(2198) (Show Source): You can put this solution on YOUR website!
Let x=amount of time Bert needs to finish the job working alone
Then Bert works at the rate of 1/x job per hour
And Mark works at the rate of 1/9 job per hour
Mark and Bert together work at the rate of 1/4 job per hour
So, our equation to solve is:
1/x + 1/9 = 1/4 multiply each term by 36x
36+4x=9x subtract 4x from each side
36=5x
x=7 1/5 = 36/5 hours
CK
1/(36/5)+1/9=1/4
5/36 +4/36 =1/4
9/36=1/4
1/4=1/4
Hope this helps--ptaylor
RELATED QUESTIONS
Jessie and Mark are planning to paint a house together. Jessie thinks that if he works... (answered by Edwin McCravy)

If A can finish a job 50% faster than B and 20% faster than C, and together they can... (answered by ankor@dixie-net.com)

Mark and Rachel both work for Smith Landscaping Co. Mark can finish a planting job in 2... (answered by VFBundy)

Mark and Rachel both work for Smith Landscaping Co. Mark can finish a planting job in 2... (answered by josgarithmetic)

How long would it take bonnie to do the job alone. If andy works twice as fast as bonnie. (answered by Cromlix)

jessie and mark are planning to paint the house together. jessie thinks that if he works... (answered by ankor@dixie-net.com)

Jessie and Mark are planning to paint a house together. Jessie thinks that if he works... (answered by josgarithmetic,MathTherapy)

Please help me solve the following problem: Mark and Rachel both work for Smith... (answered by ankor@dixie-net.com)

Solve the problem Mark and Rachel both work for Smith Landscaping Company. Mark can... (answered by mukhopadhyay)