Step 1: Determine slope using the points given and the slope formula: y₂ - y₁/x₂ - x₁.
[tex]m = \frac{1 - (-2)}{-10 - 20}\\\\m = \frac{3}{-30}\\\\m = -\frac{1}{10}[/tex]
Step 2: Determine b using one of the points listed and pluging it into the slope-intercept formula.
[tex]y = mx + b\\\\1 = -\frac{1}{10}(-10) + b\\\\1 = 1 + b\\\\0 = b[/tex]
Step 3: Put it together.
[tex]y = -\frac{1}{10}x[/tex]
