Hey there! I'm happy to help!
To find the x value of the midpoint, you add the x values and divide by 2.
3+(-9)=3-9=-6
-6/2=-3
And for the y value you add the y values and divide by 2.
-1+8=7
7/2=3 1/2
Therefore, our midpoint is (-3,3 1/2)
Have a wonderful day! :D
