SOLUTION: Ivy can do a math problem in 8 minutes, while together Iby and Lyrie can do this problem in 3 minutes. At this rate, how long does it take Lyri to do the problem by herself?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Ivy can do a math problem in 8 minutes, while together Iby and Lyrie can do this problem in 3 minutes. At this rate, how long does it take Lyri to do the problem by herself?      Log On


   



Question 834637: Ivy can do a math problem in 8 minutes, while together Iby and Lyrie can do this problem in 3 minutes. At this rate, how long does it take Lyri to do the problem by herself?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Ivy can do a math problem in 8 minutes,
while together Iby and Lyrie can do this problem in 3 minutes.
At this rate, how long does it take Lyri to do the problem by herself?
:
We will assume Ivy and Iby work at the same rate
:
Let L = Lyri's time to do the job by herself
Let the completed job = 1
:
Each will do a fraction of the job, the two fractions will add up to 1
3%2F8 + 3%2FL = 1
Multiply by 8L, cancel the denominators and we have:
3L + 3(8) = 8L
3L + 24 = 8L
24 = 8L - 3L
24 = 5L
L = 24/5
L = 4.8 minutes