To do this, find the slope, y-intercept, and your goal.
Your goal is 500.
Your slope is 6.25 per orange.
Your y-intercept is 0 (you don't start out with anything.)
So, the inequality is

.
11-5=6
18-11-7
26-18=8
........... so on and so forth.
I think you get the point.
Answer= $138.98
47.86-25.20+52.75-22.04-8.50+94.11=$138.98