Question 602437
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Hi,

M(-7, 6) is the midpoint of line RS. If S has coordinates (0, 9), 

Midpoint Pt(x,y):  ( {{{(x[1] + x[2])/2}}}, {{{(y[1] + y[2])/2  )}}})
 {{{(0 + x[2])/2 = -7}}}           therefore {{{x[2]}}} = -14 
{{{(9 + y[2])/2  )}}} = 6          therefore {{{y[2]}}} = 3 

coordinates of R are(-14,3)