Answer
Since $\det(A)\neq 0$, then the system has a unique solution.
Work Step by Step
Let $A$ be the coefficient matrix which is given by
$$A=\left[ \begin {array}{cccc} 5&4\\ -1&1
\end {array} \right]
.$$
One can calculate $\det(A)$ as follows
$$\det(A)=(5)(1)-(4)(-1)=5+4=9.$$
Since $\det(A)\neq 0$, then the system has a unique solution.
