Answer:
62 degrees
Step-by-step explanation:
the base angles are congruent and the sum of angles is 180 degrees
56 + 2x = 180
2x = 124
x = 62 degrees
If 5x=-20 then it would be

adding 2 and subtracting 2 they cancel out so its

and if you subtract 2 from negative 18 it is negative 20 so it is true
well, the assumption is that is a rectangle, namely it has two equal pairs, so we can just find the length of one of the pairs to get the dimensions.
hmmmm let's say let's get the length of the segment at (-1,-3), (1,3) for its length
and
the length of the segment at (-1, -3), (-4, -2) for its width
![\bf ~~~~~~~~~~~~\textit{distance between 2 points} \\\\ (\stackrel{x_1}{-1}~,~\stackrel{y_1}{-3})\qquad (\stackrel{x_2}{1}~,~\stackrel{y_2}{3})\qquad \qquad d = \sqrt{( x_2- x_1)^2 + ( y_2- y_1)^2} \\\\\\ \stackrel{length}{L}=\sqrt{[1-(-1)]^2+[3-(-3)]^2}\implies L=\sqrt{(1+1)^2+(3+3)^2} \\\\\\ L=\sqrt{4+36}\implies L=\sqrt{40} \\\\[-0.35em] ~\dotfill](https://tex.z-dn.net/?f=%5Cbf%20~~~~~~~~~~~~%5Ctextit%7Bdistance%20between%202%20points%7D%20%5C%5C%5C%5C%20%28%5Cstackrel%7Bx_1%7D%7B-1%7D~%2C~%5Cstackrel%7By_1%7D%7B-3%7D%29%5Cqquad%20%28%5Cstackrel%7Bx_2%7D%7B1%7D~%2C~%5Cstackrel%7By_2%7D%7B3%7D%29%5Cqquad%20%5Cqquad%20d%20%3D%20%5Csqrt%7B%28%20x_2-%20x_1%29%5E2%20%2B%20%28%20y_2-%20y_1%29%5E2%7D%20%5C%5C%5C%5C%5C%5C%20%5Cstackrel%7Blength%7D%7BL%7D%3D%5Csqrt%7B%5B1-%28-1%29%5D%5E2%2B%5B3-%28-3%29%5D%5E2%7D%5Cimplies%20L%3D%5Csqrt%7B%281%2B1%29%5E2%2B%283%2B3%29%5E2%7D%20%5C%5C%5C%5C%5C%5C%20L%3D%5Csqrt%7B4%2B36%7D%5Cimplies%20L%3D%5Csqrt%7B40%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill)
![\bf (\stackrel{x_1}{-1}~,~\stackrel{y_1}{-3})\qquad (\stackrel{x_2}{-4}~,~\stackrel{y_2}{-2})\qquad \qquad d = \sqrt{( x_2- x_1)^2 + ( y_2- y_1)^2} \\\\\\ \stackrel{width}{w}=\sqrt{[-4-(-1)]^2+[-2-(-3)]^2}\implies w=\sqrt{(-4+1)^2+(-2+3)^2} \\\\\\ w=\sqrt{9+1}\implies w=\sqrt{10} \\\\[-0.35em] ~\dotfill\\\\ \stackrel{\textit{area of the rectangle}}{A=Lw}\implies \sqrt{40}\cdot \sqrt{10}\implies \sqrt{400}\implies \boxed{20}](https://tex.z-dn.net/?f=%5Cbf%20%28%5Cstackrel%7Bx_1%7D%7B-1%7D~%2C~%5Cstackrel%7By_1%7D%7B-3%7D%29%5Cqquad%20%28%5Cstackrel%7Bx_2%7D%7B-4%7D~%2C~%5Cstackrel%7By_2%7D%7B-2%7D%29%5Cqquad%20%5Cqquad%20d%20%3D%20%5Csqrt%7B%28%20x_2-%20x_1%29%5E2%20%2B%20%28%20y_2-%20y_1%29%5E2%7D%20%5C%5C%5C%5C%5C%5C%20%5Cstackrel%7Bwidth%7D%7Bw%7D%3D%5Csqrt%7B%5B-4-%28-1%29%5D%5E2%2B%5B-2-%28-3%29%5D%5E2%7D%5Cimplies%20w%3D%5Csqrt%7B%28-4%2B1%29%5E2%2B%28-2%2B3%29%5E2%7D%20%5C%5C%5C%5C%5C%5C%20w%3D%5Csqrt%7B9%2B1%7D%5Cimplies%20w%3D%5Csqrt%7B10%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20%5Cstackrel%7B%5Ctextit%7Barea%20of%20the%20rectangle%7D%7D%7BA%3DLw%7D%5Cimplies%20%5Csqrt%7B40%7D%5Ccdot%20%5Csqrt%7B10%7D%5Cimplies%20%5Csqrt%7B400%7D%5Cimplies%20%5Cboxed%7B20%7D)