Peter and Pippin are peeling pails of potatoes. The two pails contain the same number of identical potatoes, and they begin peeling at the same time, working at constant rates. A half hour later Peter has just completed his pail, while Pippin is only two-thirds of the way through his pail. If Peter immediately joins Pippin, then how long will it take, in minutes, for the two of them to polish off peeling the rest of Pippin's potatoes?
the job remaining is 1/3 pail of potatoes
Pippin will require 50% more time to go from 2/3 to 3/3 or 15 minutes
Peter by himself could do the 1/3 pail in 10 minutes
1/10 + 1/15 = 1/x solve for x = 6 minutes