Please help out with this answer

Answer:
see below
Step-by-step explanation:
Hi!
[tex]\frac{1}{21-20} \left[\begin{array}{ccc}-3&10&\\2&-7&\end{array}\right][/tex]
(Determinant is 1 in this case)
Hence the inverse is:
[tex]\left[\begin{array}{ccc}-3&10\\2&-7&\\\end{array}\right][/tex]