I guess you do not know how to solve [-75x^3 + 50x^2 + 3x -2] = 0
Well, do you know Cardano's method or Newton's method to determine the zeros? If you don't I suggest you guess a zero, after that you use long polynomial division. So what methods do you know to find zeros?
x1 = - 1/5
x2 = 1/5
x3 = 2/3
x4,5 = 0