standard_description: Use similar triangles to explain why the slope m is the same between any two distinct points on a non-vertical line in the coordinate plane; derive the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b.
problem_activity: Solve. Show or explain your work.
a.   42 × 3
b.   6 × 215
c.   2,039 × 8


aligns: no