A plumber charges $24/hr and her apprentice assistant receives $16/hr.

Question

A plumber charges $24/hr and her apprentice assistant receives $16/hr. The bill for a particular job came to

$204, which also included a $55 charge for parts and a $25 charge for the service call. If the assistant worked

one hour less than the plumber, determine how long each worked.

Answer 1

plumber hours=x

assistant hours=y

x= y+1

The $55 parts charge and $25 service call charge have no effect on the hourly rate or how long they worked, so we will subtract those amounts from the $204 bill: 204-55-25= $124

Now we know that the plumber, who worked for $24* x hours, and the assistant, who worked for $16*y hours, together made $124.

124= 24x + 16y

--> substitute in the x=y+1

124= 24(y+1) +16y

124= 24y + 24 +16y

--> subtract 24 from both sides and then add the y's together on the right side

100=40y

---> divide both sides by 40

y= 2.5 hours

Since we know that x=y+1, then x=3.5 hours.

Hope this helped!