Rob works part time at the fallbrook riding stable. he makes $5 an hour exercising horses and $10 hour cleaning stalls. because rob is a full time student he can work no more than 12 hours per week. however he must make $60 per week.

 5x + 10y ≥ 60 ⇒ x+2y ≥ 12           (i)  

                x + y ≤ 12                                     (ii)  

Step-by-step explanation:

    Let the hours spent on exercising horse be x

    Let the hours spent on cleaning stalls be y

According to question:

Rob can't work more than 12 hours. So eq. (i) will be x + y ≤ 12

Rob earns $5 an hour by exercising horses and $10 an hour cleaning stalls and he must make $60 . So eq. (ii) will be 5x + 10y ≥ 60.

Dividing eq. (ii) by 5, it will become x + 2y ≥ 12.

∴ system of inequalities are x + y ≤ 12 and x + 2y ≥ 12.