Question 259032
We really have 2 coordinates in disguise here:
(0,1600) and (40,1200)
step 1 - we can find the slope as
{{{m = (y2-y1)/(x2-x1)}}}
putting in our x,y information, we get
{{{m = (1600-1200)/(0-40)}}}
which means 
{{{m = -10}}}
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step 2 - find the value of b using 
y=mx+ b.
picking a point and using our slope, we get
 {{{1600 = (-10)0 + b}}}
{{{b = 1600}}}
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step 3 - write the answer as
{{{y = -10x + 1600}}}