Question 649686
M = {{{(x[1]+x[2])/2}}},{{{(y[1]+y[2])/2}}}

x1 = -2
x2 = 5
y1 = 0
y2 = 3

M = {{{(-2+5)/2}}}, {{{(0+3)/2}}} = ({{{3/2}}},{{{3/2}}})

Hopes this helps! 
-Devin 
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