Question 160716
Did you mean d(x)=8-x??
I hope so. 
Pick a range of x values.
Let's choose (-3,3).
Make a table of values,
x=-3,d(-3)=8-(-3)=11
x=-2,d(-2)=8-(-2)=10
x=-1,d(-1)=8-(-1)=9
x=0,d(0)=8-(0)=8
x=1,d(1)=8-(1)=7
x=2,d(2)=8-(2)=6
x=3,d(3)=8-(3)=5
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{{{drawing( 300, 300, -4, 4, -2, 12,grid( 1 ),
circle( -3, 11, .2 ),
circle( -2, 10, .2 ),
circle( -1, 9, .2 ),
circle( 0, 8, .2 ),
circle( 1, 7, .2 ),
circle( 2, 6, .2 ),
circle( 3, 5, .2 )
)}}}
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.
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Then connect the points with a line,
{{{drawing( 300, 300, -4, 4, -2, 12,grid( 1 ),
circle( -3, 11, .2 ),
circle( -2, 10, .2 ),
circle( -1, 9, .2 ),
circle( 0, 8, .2 ),
circle( 1, 7, .2 ),
circle( 2, 6, .2 ),
circle( 3, 5, .2 ),

blue(line( -5, 13, 5, 3)))}}}