Chapter 7. Systems of Equations: Know what you don’t know

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You can graph equations with two unknowns, but can you actually solve them? You’ve been graphing all kinds of expressions lately: C and t, x, and y, and more. But what about actually solving equations with two variables? That’s going to take more than one equation. In fact, you need an equation for every unknown you’ve got. But what then? Well, a little substitution, a few lines, and an intersection are all you need to solve two-variable equations.

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It’s New Year’s Eve, and Zach has a bunch of people coming in just an hour. Problem is, he hasn’t made drinks yet...

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