SOLUTION: Mary can shovel snow from her driveway in 40 minutes. Bill can do the same job in 65 minutes. How long would it take Mary and Bill to shovel the driveway if they worked together.

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Mary can shovel snow from her driveway in 40 minutes. Bill can do the same job in 65 minutes. How long would it take Mary and Bill to shovel the driveway if they worked together.      Log On


   

Question 442694: Mary can shovel snow from her driveway in 40 minutes. Bill can do the same job in 65 minutes. How long would it take Mary and Bill to shovel the driveway if they worked together.
Found 2 solutions by josmiceli, Alan3354:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of shoveling
Mary's rate: +1%2F40+
Bill's rate: +1%2F65+
Let t = their time working together
+1%2F40+%2B+1%2F65+=+1%2Ft+
Multiply both sides by LCD +520t+
+13t+%2B+8t+=+520+
+21t+=+520+
+t+=+24.76+
They will take 24.76 minutes working together

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Don't try to remember how to do it, or remember a formula.
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Mary does 1/40 of the drive per minute.
Bill does 1/65 per minute.
That makes sense, right? Then,
Together, they do 1/40 + 1/65 per minute
Add those
= (65 + 40)/2600 per minute = 105/2600 per minute
That means,
--> 2600/105 mins per driveway
= 520/21 minutes