SOLUTION: peter can crack the can in 30 minutes. renato can crack he can in 40 minutes. after working together for 20 minutes, badong helped them and finish the job in 2 minutes. if badong w

Question 899885: peter can crack the can in 30 minutes. renato can crack he can in 40 minutes. after working together for 20 minutes, badong helped them and finish the job in 2 minutes. if badong will do the entire job alone, for how long will it take him to finish the job?
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
The problem is peter and renato already finished the job in less than 18 minutes.
a=30
b=40
1/a+1/b=1/x
1/30+1/40=1/x
1/30+1/40=1/17.1428571
1/x=1/17.1428571
x=17.1428571 minutes working together
check
1/a+1/b=1/x
1/30+1/40=1/x
40/1200+30/1200=1/x
70/1200=1/x
1200/70=x
x=17.1428571
ok

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