Susan earns $10 per hour tutoring elementary students in math. She also earns $15 per
hour cleaning in the library. Her goal each week is to earn at least $240 while working no
more than 20 hours.
Let e represent the number of hours Susan works in one week tutoring elementary students,
and let c represent the number of hours Susan works in one week cleaning the library.
Which inequalities represent Susan's weekly goal of earning money?