SOLUTION: Pls. help me with this HW problem. I've tried using the formula, WR x WT = work done, but have not gotten to the correct answer. I used {(1/40 x 20)+ (1/x x 10) = 1} Reading thr

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Question 129692This question is from textbook Alegbra Structure and Method
: Pls. help me with this HW problem. I've tried using the formula, WR x WT = work done, but have not gotten to the correct answer. I used {(1/40 x 20)+ (1/x x 10) = 1}
Reading through the problem I think the answer is 40 but I can't figure out the equation.
The problem is:
Chuck can shovel snow off his driveway in 40 min. He shovels for 20 min. and then is joined by Joan. If they shovel the remaining snow in 10 min., how long would it have taken Joan to shovel the driveway alone?
Thank you.
AV This question is from textbook Alegbra Structure and Method

Answer by oscargut(2103) About Me  (Show Source):
You can put this solution on YOUR website!
Chuck can shovel snow off his driveway in 40 min. He shovels for 20 min. and then is joined by Joan. If they shovel the remaining snow in 10 min., how long would it have taken Joan to shovel the driveway alone?
Let x = time that Joan can shovel the driveway alone
in 20 min 1/2 of the work is done
in 10 min Chuck does 1/4 of the work
so Joan did (1-1/2-1/4)=1/4 of the work in 10 min
in 1 min Joan can do 1/x of the work
then in 10 min Joan can do 10/x of the work
then 10/x=1/4 then x=40
R: 40 min