Cara and Jena, working together, can clean the house in 4 hours. Working alone, Jena takes twice as long as Cara. How long does it take Cara to clean the house alone?

hrs/house

Step-by-step explanation:

Rate is the amount of work done per unit of time;

  Let Cara's rate  = C

   Let Jena's rate  = J

        C + J  = 4  ------ i

Now;

  Working alone:

             Jena takes twice as long as Cara

                          J  = 2C  ---- i

How long does it take Cara to clean a house alone

           C + J  = 4

             J = 2C

        C + 2C = 4

           3C = 4

              C = hrs/house

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value