# Write an Equation the Represents a Proportional Relationship Between Total Cost and Number of Items

##### This Write an Equation the Represents a Proportional Relationship Between Total Cost and Number of Items video also includes:

Equations can be used to express proportions with y=mx once we solve for the constant. The video introduces the constant of proportionality at the beginning and goes into more detail at the end. The example shares the cost of a whole pizza that needs to be broken down into its cost per slice. Give your mathematicians extra time to calculate on their own and then watch how the video shows the proportion with a table and graph. The unit cost is then plugged into the formula to demonstrate how your learners can use it for future problems.

CCSS: Designed

##### Classroom Considerations

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##### Pros

• Explains the constant of proportionality and its similarity to unit cost
• Project-based activity listed in slides under resources
• Use guided practice and slides for additional problems and resources
##### Cons

• Initial slide about the equation can be confusing based on color coding and solving for m
• Constant of proportionality may still be difficult for some learners