If $a\ast b=(a\times b)+b$, then $5\ast 7$ is equal to

The binary operation is defined as:
$$a\ast b=(a\times b)+b$$
To find the value of $5\ast 7$, substitute $a=5$ and $b=7$ into the definition:
$$5\ast 7=(5\times 7)+7$$
$$5\ast 7=35+7=42$$