7. A student has started a lawn care business. He charges $15 per hour to mow lawns and $20 per hour for gardening. Because he is still in school, he is only allowed to work for at most 20 hours
per week. His goal is to make at least $300 per week.
a. Create a system of equations or inequalities that models the situation. Define the variables you
use.
b. The graph shows one of the relevant equations in this situation. Draw the graph of the other
relevant equation.