$6 ? 5+4 =9
9-3 =6
I don't know if this is correct but this is how I would do it
Answer:

Step-by-step explanation:
Because we are told equivalent expressions for y and z we can plug those in to 2(y+z).

Then simplify by combining like terms of the expressions. Values ending in x^2 can be combined with each other.

Now we can distribute the 2 by multiplying each value in the parentheses by 2.

Independent - Size/Type of pizza
Dependent - The cost of pizza