### Home > CAAC > Chapter 8 > Lesson 8.2.1 > Problem8-46

8-46.

Find the equation of the line that goes through the points $(-15,70)$ and $(5,10)$.

One strategy is to graph the two points and make a slope triangle to find the slope of the line.

Use the slope triangle to find the slope of this line.

$m=\frac{\Delta y}{\Delta x}=\frac{-60}{20}$

Substitute a pair of coordinates for $x$ and $y$ and the slope to solve for $b$.
$y=mx+b$
$10=−3(5)+b$
$10=−15+b$
$25=b$

Substitute the values found for $m$ and $b$ into the equation of the line.

Use the eTool below to help solve the problem.
Click the link at right for the full version of the eTool: CCA 2-91 HW eTool