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: A system of linear equations is represented in the graph below.
[IMG]
a.   Write the two equations that represent this system.
b.   What is the solution to the system? Prove this algebraically.


aligns: no