f(x)=(1-6t)(3+t)

Solution for f(x)=(1-6t)(3+t) equation:

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

Multiply f * x
fx = (1 + -6t)(3 + t)

Multiply (1 + -6t) * (3 + t)
fx = (1(3 + t) + -6t * (3 + t))
fx = ((3 * 1 + t * 1) + -6t * (3 + t))
fx = ((3 + 1t) + -6t * (3 + t))
fx = (3 + 1t + (3 * -6t + t * -6t))
fx = (3 + 1t + (-18t + -6t2))

Combine like terms: 1t + -18t = -17t
fx = (3 + -17t + -6t2)

Solving
fx = 3 + -17t + -6t2

Solving for variable 'f'.

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

Divide each side by 'x'.
f = 3x-1 + -17tx-1 + -6t2x-1

Simplifying
f = 3x-1 + -17tx-1 + -6t2x-1

Reorder the terms:
f = -17tx-1 + -6t2x-1 + 3x-1