Factor f(x)=4x²-15x-25 and then use zero-product property to find the zeros of the quadratic function. show all work (will mark brainliest) [pre calculus]

f(x)=4x²-15x-25
f(x)=(4x + 5)(x - 5)

zero-product property 
let f(x)=(4x + 5)(x - 5) = 0
so
(4x + 5)(x - 5) = 0
4x +5 = 0
4x = -5
  x = -5/4
  x = -1.25

x - 5 =0
x = 5

answer
factor: (4x + 5)(x - 5)
x = 5 and x = -1.25

I’m not sure how this works