Answer:
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