\(m = \frac{y_{2} - y_{1}}{x_{2}- x_{1}} = \frac{15 - (-10)}{-15 - 6} = \frac{15 + 10}{-21} = \frac{25}{-21} = -1\frac{4}{21}\)
y - y₁ = m(x - x₁)
y - (-10) = -1⁴/₂₁(x - 6)
y + 10 = -1⁴/₂₁(x) + 1⁴/₂₁(6)
y + 10 = -1⁴/₂₁x + 7¹/₇
- 10 - 10
y = -1⁴/₂₁x - 3¹/₇
