How much do you pay each class? Should we add any flat rates?
Rule in Words: Multiply the number of classes by 15 and add 20. Rule as an Algebraic Expression: 15n+20
Practice makes perfect
We are asked to write this situation as a rule in words and as an algebraic expression. Let's write it using words first, then use that to create our algebraic expression.
Rule in Words
The dance classes cost $15 per class. This means that we can find the total cost of the dance classes, without including the registration fee, by multiplying 15 by the number of classes we are taking. Let's look at a few examples of how this works.
Number of Classes
Cost Calculation
Cost of Classes
1
(1* 15)
$15
2
(2* 15)
$30
3
(3* 15)
$45
Now, we also have to include the registration fee. It is equal to $20 no matter how many classes you take. We will add $20 to the cost of the lessons regardless of the number of classes taken. Let's include this in our table.
Number of classes
Cost Calculation
Cost of Classes
Plus Fee
Total Cost
1
(1 * 15)
$15
$15+$20
$35
2
(2 * 15)
$30
$30+$20
$50
3
(3 * 15)
$45
$45+$20
$65
Thus, we can write this rule in words as follows.
Multiply the number of classes by 15
and add20.
Rule as an Algebraic Expression
To write the rule as an algebraic expression, we first need to assign a variable to the number of classes. We can say that n represents the number of classes taken. This gives us the following rule.
Multiply the number of classes by $15$
and add $20$. [0.8em]
15 * n + 20 ⇔ 15 n + 20
