Set up the following equations:


x is the amount of hours worked on the weekday job, and y is the amount of hours worked on the weekend job.
We'll use substitution to remove one of the variables.
Multiply the first equation by -18 to get opposite coefficients for y:


Combine these two equations together:

Divide both sides by 2 to get x by itself:

Plug in x to the first original equation:

Subtract 25 from both sides to get y by itself:

He worked
25 hours at his weekday job, and 15 hours at his weekend job.