as we know how to find midpoint.
the formula is = (x1 + x2/2 , y1 + y2/2 )
and the given values are one endpoint and midpoint so, just insert the given values in midpoint's formula..and u will get the value of other end point.
hope this answer helps you dear...take care and may u have a great day ahead!
if u have any doubt or dissatisfaction with the explanation...feel free to ask I will tell u more briefly.
