SOLUTION: Butch and Peggy want to pick up the mess that their grandson has made in the playroom. Butch can do it in 15 min working alone. Peggy, working alone can clean it up in 12 min. How

Question 434762: Butch and Peggy want to pick up the mess that their grandson has made in the playroom. Butch can do it in 15 min working alone. Peggy, working alone can clean it up in 12 min. How long will it take them if they do it together?
I set it up as 180(X/15+ X/12=1)180
= 12X+15X=180
= 9X=180
= -- ---
9 9
X=20
UNSURE ABOUT MY FINAL ANSWER THOUGH
Answer by jorel1380(3719) (Show Source): You can put this solution on YOUR website!
If Peggy can clean up in 12min., then she does 1/12 a job per minute. Likewise, Butch's time is 1/15 job per minute. Then;
1/12+1/15=1/t, t being the time it takes them working together.
Multiply both sides by 60t:
5t+4t=60
9t=60
t=60/9 minutes or 20/3 minutes.
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