Jessica is selling books during the summer to earn money for college. She earns a commission on each sale but has to pay for her
own expenses. After a month of driving from neighborhood to neighborhood and walking door-to-door, she figures out that her weekly earnings are approximately a linear function of the number of doors she knocks on.
She writes the equation of the function like this: E(x) = 7x - 25, where x is the number of doors she knocks on during the week and E(x) is her earnings for the week in dollars.
What does the slope of Jessica's function represent?
