[tex](-800,200), \ \ \ \(-400,300) \\ \\ first \ find \ the \ slope \ of \ the \ line \ thru \ the \ points \: \\ \\ m= \frac{y-y_{1}}{x-x_{1} } \\ \\m=\frac{200-300 }{-800+400} = \frac{-100}{-400}=\frac{1}{4} \\ \\Now \ use \ y = mx + b \ with \ either \ point \ to \ find \ b, \ the \ y-intercept \ : \\ \\ y=mx+b \\ \\200= \frac{1}{4} \cdot(-800)+b\\ \\200=-200 +b \\ \\b=200+200=400 \\ \\ y= \frac{1}{4}x+400 \ is \ the \ answer
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