Thanks for reaching out! You’re right in that Phases 2 and 3 are about building the two equations to create the system. Phase 4 is about analyzing what the system tells us. To find the break even point (question 9) students need to calculate the solution to the system. While questions 8 and 10 can be answered using just one of the two equations, questions 11 and 12 require using both. I’m remembering now that one year I needed to clarify that questions 11 and 12 were about profit, not just revenues. (I’ll update that on the assignment now!) To solve 11, students need to transform one of the equations before solving (+/- $1000). To solve 12, students need to plug in 500 for both and find the difference between the answers.