To multiply 7(b-5)(b-4), you can follow these steps:
1.
Start by distributing the 7 to the terms inside the parentheses:
7(b-5)(b-4) = 7 * b * (b-4) - 7 * 5 * (b-4)
2.
Simplify each term using the distributive property:
= 7b^2 - 28b - 35b + 140
3.
Combine like terms:
= 7b^2 - 63b + 140
So, the final answer is 7b^2 - 63b + 140.