Final answer:
The expression 6f - 1 + 7f - 8 simplifies to 13f - 9 by combining like terms, which involves adding the coefficients of the variable 'f' and combining the constant numbers.
Step-by-step explanation:
The expression given in the question is 6f - 1 + 7f - 8. This is a mathematical expression that combines like terms and requires simplification. To combine like terms, simply add or subtract the coefficients (numerical values) of the same variable. In this case, 6f and 7f are like terms.
Combining these like terms gives us:
This results in the simplified expression: 13f - 9. There is no other simplification or combination that can be done within this expression, as there are now no more like terms to combine.