Question 297197
{{{drawing(300,300,-8,8,-2,8,grid(1),
circle(-4,7,.2),
circle(3,6,.2),
circle(2,4,.2),
blue( line(-4,7,3,6)),
blue( line(2,4,3,6)),
locate(-4.5,7.5,A),
locate(3.5,6,B),

locate(2.5,4,C))}}}
To maintain the parallelogram, the relationship between D and A must be the same as the relationship between C and B. 
To go from C to B, you need to move {{{1}}} in the x direction, {{{2}}} in the y direction.
So then to move from D to A, you need to move the same.
{{{x+1=-4}}}
{{{x=-5}}}
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{{{y+2=7}}} 
{{{y=5}}}
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{{{drawing(300,300,-8,8,-2,8,grid(1),
circle(-4,7,.2),
circle(3,6,.2),
circle(2,4,.2),
circle(-5,5,.2),
blue( line(-5,5,-4,7)),
blue( line(-5,5,2,4)),
blue( line(-4,7,3,6)),
blue( line(2,4,3,6)),
locate(-5.5,5,D),
locate(-4.5,7.5,A),
locate(3.5,6,B),
locate(2.5,4,C))}}}
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D:({{{-5}}},{{{5}}})