Negative 13j is the solution to your problem.
Y has a coefficient of 1 in the first equation, so it is easiest to use that one to write an expression for y.
... y = 20 - 2x . . . . . subtract 2x
Now, this expression can be substituted for y in the second equation.
Then, using the expression for y, we find its value
... y = 20 -2·7 = 6
The solution of the equations is (x, y) = (7, 6).
The solutions to a system of simultaneous equations are the points
where their graphs intersect.
If the equations are both linear, then their graphs are both straight lines.
If their slopes are not the same, then there can only be one solution,
because the lines only intersect in one point.
∠UXW = 36°
∠WZX = 66°
∠UWY = 48°
∠XYZ = 42°
Use the Alternate Exterior Angles Theorem. Always remember that a triangles angles add up 180°, so you can subtract the angles you already know in a triangle to figure out the remaining angle.