Problema Solution
Janet can wax her car in 8 hours. When she works together with Deidre, they can wax the car in 30 minutes. How Long would it take Deidre by herself to wax the car?
Answer provided by our tutors
let
x = 8 hour the time Janet needs to wax the car alone
y = the time Deidre needs to wax the car alone
in 1 hour time
Janet will finish 1/8 of the job
Deidre will finish 1/y of the job
together they will finish 1/(1/2) of the job since 30 min = 1/2 hours
thus we have
1/8 + 1/y = 1/(1/2)
1/8 + 1/y = 2 multiply both sides by 8y
y + 8 = 16y
y = 8/15 hours = 8*60/15 min = 32 min
Deidre needs 32 min to wax the car by herself.