6 5/21
I do t have anything else to put here I just needed 20 characters to give u this answer so here
Answer and Step-by-step explanation:

Decreased by 20%
F(x^2) = x^2 - 3
5f(x^2) = 5x^2 - 15 = 2x - 8
Placing all the terms on the left side, we get:
5x^2 - 2x - 7 = 0 which factorises to
(5x - 7)(x + 1) = 0
So, x = 7/5 or x = -1
But x is non-negative, so x = 7/5 = 1 2/5
C is the answer.
The answer is a so have a good day