On a standard die with six faces, each face contains a different number from 1 through 6. Jake has a non-standard die with six faces, and each face on Jake's die contains an expression with a different value from 1 through 6. In no particular order, the six expressions are $a + 1$, $2a - 5$, $3a - 10$, $b + 8$, $2b + 5$ and $3b + 10$. If $a$ and $b$ are integers, what is the value of the product $a \times b$?