Ming drew a triangle. the sum of the angles of the triangle is 180º.

(rest attached as images)

The second matrix

If we want to write a proper matrix to represent the given system of equations, we have to arrange it in order:

After this, we can write the matrix with the coefficients of each equation:

Being this, the matrix that represents the measure of each angle in Ming's triangle

thats not a system of equations, that is a solution