Question 846985
Here's what the plots of these 2 
equations look like:
{{{ graph( 500, 500, -8, 8, -8, 16, 2x, -2x + 8 ) }}}
The way you plot each line is to pick
a value for {{{ x }}} and then find {{{ y }}}
that will give you a point on the line ( x,y )
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For example, say you're plotting
{{{ y = -2x + 8 }}}
I'll pick {{{ x = -1 }}} 
{{{ y = -2*(-1) + 8 }}}
{{{ y = 2 + 8 }}}
{{{ y = 10 }}}
so, you have the point ( -1, 10 ) on the line
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Just keep doing this with small whole numbers
for each of the lines, and you should end up 
with 2 lines that look like my plots
Hope this helps