Question 84567
Given the endpoints (7,3) and (2,1)
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The x value of the midpoint is halfway between the x value of the two endpoints. That means
that it is halfway between +7 and +2.  You can get this x value by averaging the x values
of the endpoints ... adding them together and dividing by 2.  Averaging them:
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{{{(7+2)/2 = 9/2 = 4.5}}}
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Similarly the y value of the midpoint can be found by averaging the y values of the two 
endpoints.  The y values of the endpoints are +3 and +1 and averaging them results in:
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{{{(3+1)/2 = 4/2 = 2}}}
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So the point that is the midpoint is defined by the two values as being (4.5, 2).
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Hope this helps you to see how to work midpoint problems if you are given the two endpoints
of a line.