Unit B: Proportionality

Topic 2: Proportional Relationships, Lines, and Linear Equations

2-1: Representing Proportional Relationships

Part 1

Example Graphing Proportional Relationships

A video game store has a frequent shopper program. You earn 4 points for every video game you buy. Draw a graph to model this situation.

You need 48 points for a free game. How many video games do you need to buy to have enough points for a free game?

Solution

For every game you buy, you earn 4 points. Since you can only buy entire games, it only makes sense to plot points with x-coordinates that are whole numbers. For each point on the graph, the y-coordinate should be four times the x-coordinate.

Since you need 48 points for a free game, look for a point on the graph until you reach a y-coordinate of 48.

A graph.

You need to buy 12 games to have enough points for a free game.


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Table of Contents

Digits, Grade 8, Volume 1, Homework Helper Unit A: Number and Operations Unit B: Proportionality Unit C: Expressions, Equations, and Relationships English/Spanish Glossary Formulas Math Symbols Formulas Measures Properties