well P(x) is the total money they made.
so if P(X) < 0 they had a loss.
so if you plug in 0 you get
0=-7520x^2+15000x
add 7520x^2 to both sides
7520x^2=15000x
(7520x)x is the same thing, if you multiply it out it will still equal 7520x^2
so (7520x)x=15,000x
divide both sides by x and
7520x=15,000
divide both sides by 7520
x=1.995
then you would just need to check a number on both sides,
i.e. 0 and 2
2 gives you a value of -80 which means anything greater then 1.995 would be negative