Lesson objective: Write and solve equations to represent percent decrease situations.

Students practice finding percent change by writing and solving equations. Ratio equations are used here to help students understand the connection between the values in a ratio and the percent change. This work develops students' understanding that they can use the known values in an equation to determine the value they do not yet know.

Students engage in Mathematical Practice 2: Students will reason abstractly and quantitatively as they write and solve algebraic equations to represent real life problems involving percent.

**Key vocabulary:**

- original value
- percent change
- percent decrease
- percent increase
- ratio equation

**Special materials needed:**