Can someone let me know if I simplified these equations correctly or at least show me how to do it?

Answer:
Your work is correct as far as it goes. Now eliminate the terms that are zero.
Step-by-step explanation:
Multiplying anything by zero gives zero. Adding zero is like adding nothing. Zero is called the "additive identity element" because ...
a + 0 = a
Adding zero doesn't change anything. You can (and should) drop the zero if your goal is to simplify the expression.
[tex]a. \quad x_{f}=v_{0}\\\\b. \quad x_{f}=v_{0}t\\\\c. \quad v_{f}^2=v_{0}^2[/tex]