f(x)=3-5(6-t)-2(6-t^2)

Solution for f(x)=3-5(6-t)-2(6-t^2) equation:

Simplifying
f(x) = 3 + -5(6 + -1t) + -2(6 + -1t2)

Multiply f * x
fx = 3 + -5(6 + -1t) + -2(6 + -1t2)
fx = 3 + (6 * -5 + -1t * -5) + -2(6 + -1t2)
fx = 3 + (-30 + 5t) + -2(6 + -1t2)
fx = 3 + -30 + 5t + (6 * -2 + -1t2 * -2)
fx = 3 + -30 + 5t + (-12 + 2t2)

Reorder the terms:
fx = 3 + -30 + -12 + 5t + 2t2

Combine like terms: 3 + -30 = -27
fx = -27 + -12 + 5t + 2t2

Combine like terms: -27 + -12 = -39
fx = -39 + 5t + 2t2

Solving
fx = -39 + 5t + 2t2

Solving for variable 'f'.

Move all terms containing f to the left, all other terms to the right.

Divide each side by 'x'.
f = -39x-1 + 5tx-1 + 2t2x-1

Simplifying
f = -39x-1 + 5tx-1 + 2t2x-1

Reorder the terms:
f = 5tx-1 + 2t2x-1 + -39x-1