Question 835729
The midpoint is the average of x and y values.
{{{(8+x[N])/2=8}}}
{{{8+x[N]=16}}}
{{{highlight(x[N]=8)}}}
.
.
{{{(-9+y[N])/2=7}}}
{{{-9+y[N]=14}}}
{{{highlight(y[N]=23)}}}