In this lesson, students write and solve equations involving rational expressions with different denominators and interpret the equations and solutions in context (MP2). Building on the reasoning established in the previous lesson, students continue to use strategic multiplication to change the structure of the equation to linear, which they then solve.

The Warm-up invites students to make sense of a new situation (MP1) involving distance, rate, and time for a boat traveling on a river. Building on the Warm-up, the following activity invites students to create expressions for the time it takes a boat to travel a certain distance upstream and a certain distance downstream in order to calculate the rate of flow of the water in the river. In the last activity, students work with the formula for the total resistance of circuits in parallel.

Technology isn't required for this lesson, but there are opportunities for students to choose to use appropriate technology to solve problems. We recommend making technology available.