First, distribute the parentheses:
(-3 * 2.5) + (-3 * -k) + (.5 * 7) + (.5 * 8k)
-7.5 + 3k + 3.5 + 4k
Combine like terms:
(-7.5 + 3.5) + (3k + 4k)
-4 + 7k
I don't see an equal sign so it's not an equation, just an algebraic expression, which means that the answer is -4 + 7k