Question 98384
Holly can do 1/50 of the job per minute
Erich can do 1/60 of the job per minute
Holly works alone for 10 min. she does 10/50 or 1/5 of the job.
both together = 1/50+1/60=6/300+5/300=11/300 job per minute.
t=time in minutes
11t/300=4/5
t=4/5*(300/11)=21 9/11minutes
So the total time it takes is 21+10= 31 minutes and 49 seconds(9/11*60)
Ed