if john can wax his car in 3 hours and jim can do the same job in 5 hours how long will it take them if they work together

Question

Please show how to solve the problem

 

Answer 1

Hi Missy, with these types of problems, the way to solve them is to look at how much work they can do in one hour.

 

John: In one hour, he can do 1 / 3 of the work.

 

Jim: In one hour, he can to 1 / 5 of the work.

 

Together: In one hour, they can do 1 / x of the work.

 

Equation:

 

1 / 3 + 1 / 5 = 1 / x

 

To clear the fractions, multiply the entire equation by 15x:

 

15x * (1 / 3 + 1 / 5 = 1 / x)

 

5x + 3x = 15

 

8x = 15

 

Divide both sides by 8:

 

x = 15 / 8

 

John and Jim working together can wax the car in 15 / 8 hours or 1 and 7/8 hours.

 

Questions?