A binary operation $\ast$ on the set $\{0, 1, 2, 3, 4, 5\}$ is defined as $a * b= \left\{ \begin{array}{1 1} a+b & \quad if\;a+b < 6\\ a+b-6 & \quad if a+b \geq 6 \end{array} \right.$

Question

$\begin{array}{1 1}1) True \quad 2) 6 - a \\ 1) True \quad 2) 6 - b \\ 1) False \quad 2) a - 6 \\ 1) False \quad 2) a\end{array}$