To solve the expression:

$-10(8f - 9f - 9) - 7f$

Step-by-step:

1. Simplify inside the parentheses: $8f - 9f = -f$ So the expression inside the parentheses becomes: $-f - 9$

2. Distribute the -10 to each term inside the parentheses: $-10(-f - 9) = 10f + 90$

3. Now substitute back into the original expression: $10f + 90 - 7f$

4. Combine like terms (combine $10f$ and $-7f$): $(10f - 7f) + 90 = 3f + 90$

Thus, the simplified expression is:

$3f + 90$

Would you like more details on any specific step?

Related Questions:

1. How do you solve equations with variables on both sides?
2. How do you distribute negative numbers in an expression?
3. Can you explain how to combine like terms in more detail?
4. What happens when a variable is eliminated from both sides of an equation?
5. How do you factor expressions with multiple terms?

Tip:

Always simplify expressions inside parentheses first before applying operations like distribution!