Which input value produces the same output value for the two functions?

In trapezoid efgh, m∠hef=(4x2+16)∘ and m∠gfe=(5x2+12)∘. find the value of x so that efgh is isosceles. i'm desperate.

Y=(x+3)(x-4)(x+1)^2 sulutions? multiplicity?

2x minus y equals 6, x plus y equals negative 3