- Midpoint Formula:

So firstly, let's start with the x-coordinates. Since we know the midpoint's x-coordinate and point A's x-coordinate, we can solve for point B's x-coordinate as such:

Next, do the same thing except solve for the y-coordinate and using point A's y-coordinate and the midpoint's y-coordinate:

<u>Putting it together, point B's coordinates are (2,4).</u>
9x² + bx + 64
\/(9x²) = 3x
\/84 = 8
2*3x*8 = 48x
b = 48