You can put this solution on YOUR website! Midpoint is half of the x values (the mean or average of the two) and half the y-values.
x values are -9 and 8. Add them (-1). Take half of it (-1/2)
y values are -2 and 6. Add them (4). Take half (2)
The midpoint is (-1/2,2)
The line shown has the x-values at the end. The midpoint will be (-1/2.2)