Final answer:
In the expression 12+5(-3n-8), the factors are -3n-8 and 5, as they are the parts being multiplied together.
Step-by-step explanation:
When asked, "What part of the expression is a factor?" in relation to the expression 12+5(-3n-8), it's important to identify the multiplied elements within the mathematical expression. A factor is a number or expression that is multiplied by another number or expression to get a product. In the given expression, the part within the parentheses, -3n-8, is being multiplied by 5. Therefore, -3n-8 and 5 are factors in the expression 5(-3n-8).