Question

You earn $11 per hour delivering pizzas. you also work part-time at a convenience store where you earn $9 per hour. you want to earn at least $150 per week, but you can only work 25 hours per week. how many hours can you work at each job?

Answer 1

We will traduce the sentences into equations. 
Let x be the number of hours in the first job, and y be the number of hours in the second job. 
Then the equations are:
$x+y\leq25\\11x+9y\geq 150$

The above system has many solution, we can select for example:
x = 1, y = 16. So we can work one hour at the first job and 16 hour at the second job.