The triangles are similar so the angles are equal
2x^2 - 2 = 10x - 2
2x^2 - 2 - 10x + 2 = 0
2x^2 - 10x = 0
2x(x - 5) = 0
2x = 0 OR x - 5 = 0
x = 0 OR x = 5
0 doesn't make sense, because IF I plug 0 into 2x^2 - 2 I get a negative number. We need to use 5 to find the angle measure
2(5^2) - 2 = 2(25) - 2 = 50 - 2 = 48 degrees or the measure of CED