Answer: 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:
![\left[\begin{array}c1&1&1&180\\2&-1&0&0\\4&0&-1&-5\end{array}\right]](https://img.qammunity.org/2020/formulas/mathematics/middle-school/2w8jfuxzzh8es74e2tnqg4slkwc9hsoz34.png)
Being this, the matrix that represents the measure of each angle in Ming's triangle