Answer:
The highest possible value of b would be 750.
Explanation:
If you graph the two equations, you'll get two crossing lines, and because y is supposed to be either equal to or less, the answer is going to be at the shaded area at the bottom.
Equate the two equations to solve them with algebra.
-15x+3000=5x
add 15x to both sides
3000=20x
divide by twenty, you get
150=x
Plug that in to both equations, you'll get y=750, which is the highest possible value of b, (aka y cuz it's on the y axis).