Question 450613
Erica can do one  math problems in two  minutes and .5 in 1 minute
Penny can do 15/25 in one minute
Another way look at it
Erica can do 30 problems in 60 minutes
So Erica can do the whole job in 60 minutes
Penny can do 30 problems in 50 minutes
Penny can do the whole job in 50 minutes
x/50+x/60=1

x/5+x/6=10
6x+5x=300
11x=300
x=300/11
x=27.27 minutes