y=-(4-x)(x+3)

Solution for y=-(4-x)(x+3) equation:

Simplifying
y = -1(4 + -1x)(x + 3)

Reorder the terms:
y = -1(4 + -1x)(3 + x)

Multiply (4 + -1x) * (3 + x)
y = -1(4(3 + x) + -1x * (3 + x))
y = -1((3 * 4 + x * 4) + -1x * (3 + x))
y = -1((12 + 4x) + -1x * (3 + x))
y = -1(12 + 4x + (3 * -1x + x * -1x))
y = -1(12 + 4x + (-3x + -1x2))

Combine like terms: 4x + -3x = 1x
y = -1(12 + 1x + -1x2)
y = (12 * -1 + 1x * -1 + -1x2 * -1)
y = (-12 + -1x + 1x2)

Solving
y = -12 + -1x + 1x2

Solving for variable 'y'.

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

Simplifying
y = -12 + -1x + 1x2