Final answer:
To simplify the expression -6(13) - 21, perform the multiplication first to get -78, and then subtract 21 to get -99.
Step-by-step explanation:
To simplify the expression -6(13) - 21, we need to follow the order of operations which states that we should perform any calculations inside parentheses first.
We have -6 multiplied by 13, which equals -78. So the expression becomes -78 - 21.
To simplify further, we subtract 21 from -78, which gives us -99. Therefore, the simplified form of -6(13) - 21 is -99.