IXL Algebra1 - U.9 Solve a System of Equations Using Substitution : Word Problems

Given situations of different starting points (y - intercepts) and differing rates (slopes), students are asked to find the "break even" points.

On the very first example, I made an error identifying the variable of interest as cars instead of days. It is a very common error due to the way the problem is described, so it is a good error to analyze and correct.