Question 895328
The midpoint is the average of the x and y values of the endpoints.
{{{x[m]=(x[1]+x[2])/2}}}
{{{10=(17+x[2])/2}}}
{{{17+x[2]=20}}}
{{{x[2]=3}}}
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{{{y[m]=(y[1]+y[2])/2}}}
{{{-1=(8+y[2])/2}}}
{{{8+y[2]=-2}}}
{{{y[2]=-10}}}