240 = 16x is about an equation but you can make it more complicated by adding unneeded parts for example 240 = 16x - 81 + ((15x) + 15) - (x^2 / 2) - 45 - 1.5.
X^2-4x+4 is the answer, to save you points next time, use an app called M8thw8y

First factor out the common x
Then you can use the quadratic equation to solve for the second order polynomial.