Y=3x
x+2y=21
What's the best method to solve the system of equations?​

Step-by-step explanation:

Step 1: y=3x

           x+2y=21

Step 2: x+2(3x)=21   (x+6x=21)

            Substitute the "y" in the second equation with the "3x."

Step 3: (7x=21)

           Combine like terms

Step 4: x=3

           Divide

Step 5: y=3(3) or y=9

            Plug in your answer to find the value of "y"

answer:

c) the x-coordinate of the center of the circle increases by 3