Step-by-step explanation:
1) Distribute the numbers outside of the parenthesis to the numbers inside the parenthesis. This means multiple the outside number to all the numbers that are inside the parenthesis:
-5+25k-8k-20
2) Combine the like terms. The number with k get combined together since they both have a k. The numbers without a k get combined together. When you combine, you ADD the numbers together.
-13k+5
That should be right!