How do you work this pro how you work this problem 2a3+5a3

What is f(3) for the quadratic function f(x)= 2x^2+ + x - 12

Ijust need to see how to do this. so you don’t have to answer all of them just a step by step explanation of one.

What would be the reasons for lines 3 and 4? a. addition property; subtraction property b. addition property; solve c. substitution property; subtraction property d. substitution property; prove