Evaluate $2 \times 2$ Determinant $$\left| \begin{array} { r r } 4 & - 6 \\7 & - 4\end{array} \right|$$

Short Answer

Evaluate $2 \times 2$ determinant. $$\left| \begin{array} { r r } 4 & - 6 \\7 & - 4\end{array} \right|$$ Please enter your answer as a number.