F(x,y) =3x + 5y (hope this helps )
Answer:
The answer for first one is,

sorry I don't know the answer for second one.
The equality used is Subtraction property of equality
Option A is correct
Step-by-step explanation:
We need to identify which option best explains or justifies Step 1.
Step 1 is: 
The given equation is: 
To get the equation for step 1 we need to subtract c on both sides of equation i.e using subtraction property of equality


So, The equality used is Subtraction property of equality
Option A is correct.
Keywords: Solving Quadratic Equations
Learn more about Solving Quadratic Equations at:
#learnwithBrainly