bar diagram, model
TEKS 7(1)(E), 7(11)(A)
A bar diagram is a model that you can use to represent part-to-whole relationships. Consider the following situation:
A company has 5 samples to ship to a client. Each sample has the same weight. A box to ship them weighs 8 ounces before it is packed. The total weight of the shipment is 47 ounces.
You can make a bar diagram to represent this situation. Let g represent the weight of one sample.
So you can represent this situation with the equation 5g + 8 = 47.
Example Using Bar Diagrams for Two-Step Equations
You and your friend play online video games. You buy 1 software package and 3 months of game play. Your friend buys 1 software package and 2 months of game play. Each software package costs $20. The total cost is $115. Make a bar diagram to find the cost of one month of game play.
Let x = the cost of one month of game play.
The equation is 115 = 5x + 40.