Answer:
60
Explanation:
We have been given the matrix;
![\left[\begin{array}{ccc}5&8\\-5&4\end{array}\right]](https://img.qammunity.org/2020/formulas/mathematics/college/zuyfsb0jg1pgxnl29yawj2h1qoadnb5dbq.png)
For a 2-by-2 matrix, the determinant is calculated as;
( product of elements in the leading diagonal) - (product of elements in the other diagonal)
determinant = ( 5*4) - (8*-5)
= 20 - (-40) = 60