Mathematics

The key here is understanding that $\otimes$ is just a custom operation—you apply the definition mechanically, working from the inside out. First evaluate $6 \otimes 4$ using the formula, then treat that result as your new $a$ and combine it with $3$ using the same rule. It's a good reminder that unfamiliar symbols are just instructions for how to combine two numbers.

The key here is understanding that $\otimes$ is just a custom operation—you apply the definition mechanically, working from the inside out. First evaluate $6 \otimes 4$ using the formula, then treat that result as your new $a$ and combine it with $3$ using the same rule. It's a good reminder that unfamiliar symbols are just instructions for how to combine two numbers.