What is the value of n in the equation below 2n+1=21

The linear combination method is applied to a system of equations as shown. 4(.25x + .5y = 3.75) → x + 2y = 15 (4x – 8y = 12) → x – 2y = 3 2x = 18 what is the solution of the system of equations? (1,2) (3,9) (5,5) (9,3)

What is the image of c for a 90° counterclockwise rotation about a? (3, 7) (-1, 3) (7, 3)

3.4a=57.8 what is the the value of a