If the midpoint between (x, 7) and (10, 11) is (15, 9), find the value of x.

The midpoint between two endpoints is just the average of the coordinates of the endpoints.

p=((x1+x2)/2+(y1+y2)/2), in this case:

So the x value of the midpoint is:

mp=(x1+x2)/2  and we are told mp=15 and x2=10 so

15=(x+10)/2

30=x+10

20=x so

x=20

21/2 or 5/2

C, e, and a (hope it )