### Instruction: Evaluate $6+5-4\times 3\div (2+1).$.### Response: This problem involves order of operations, which tells me to do parentheses, exponents, multiplication and division, and addition and subtraction in that order.
I start with the parentheses and see that $2+1$ is $3$.
Then I do the multiplication and division from left to right and see that $4\times 3$ is $12$ and $12\div 3$ is $4$.
So I can rewrite the expression as $6+5-4$.
Finally, I do the addition and subtraction from left to right and see that $6+5$ is $11$ and $11-4$ is $7$.
So the final answer is $7$.