Expert: Lynn Houston - 1/20/2010

Question
I'm not sure you received my question when I sent it. Here I go again, I'm sorry if you already did.

Sandie can complete her paper route in 45 minutes. When her sister Christina helps her, it takes them 18 minutes to complete the route. How long would it take Christina alone to complete the route?

Answer
in 1 minute, Sandie can do 1/45 of her route and together they can do 1/18, so 1/45 + x = 1/18
x = 1/18 - 1/45
x = 45/810 - 18/810
x = 27/810 = 1/30 so Christina can do 1/30 of her route in 1 minute, which means she can complete her route by herself in 30 minutes