HKIMO 2019 Grade 6 National Final (Heat) Set 02 Question 13

For $a\ne3$, define $a\otimes b=\frac{3ab}{a-3}+2b$. Find $6\otimes(10\otimes7)$.

Source glossary (English–Vietnamese): Define: định nghĩa; Operation symbol: phép toán; Value: giá trị.