Jena and Cindy, Working together can clean the house in 10 hours. Working alone, cindy takes twice as long as jena. How longs does it take jena to clean the house.

Answer 1

Let Jena time alone be x hrs
let Cindy's time alone be 2x hrs

let the two rates be
1/x and 1/(2x)
combined rate = 1/x + 1/(2x) = 3/(2x)
1/(3/(2x)) = 10
2x/3 = 10 hrs =
2x = 30 or x = 15

Jena will take 15 hrs to do the house alone