Concept

Variable term: An unknown number in an equation.

Rule

  To solve for a variable term:

1. Fill in the known quantities in the equation below:
    The total amount of money = (cost per item) × (number of items) + cost of a single item
2. Use a variable for the unknown number.
3. Solve for the variable by isolating it on one side of the equation.
   a) add or subtract the constant on the same side of the equation as the variable.
   b) eliminate the coefficient of the variable through multiplication or division.

Example

Sasha took her friends to the movie theatre. She paid 34 dollars for movie tickets and 2 dollars for each box of candy. She spent a total of 42 dollars. How many boxes of candy did Sasha buy? 

Solution

4 boxes of candy

1. Fill in the known quantities in the equation below:
   Total amount of money = (cost per item) × ( number of items) + cost of a single item
   42 = 2 x boxes of candy + 34
2. Use a variable for the unknown number. The boxes of candy is the unknown number.
   42 = 2y + 34
3. Solve for the variable by isolating it on one side of the equation.
   First, subtract or add the constant on the same side of the equation as the variable.

   	42	=	2y	+	34
   −	34	=		−	34
   	8	=	2y

   Second, eliminate the coefficient of the variable through multiplication or division.
   82 = 2y2 
   
   4 = y

Pre-requisite Skills

Solve Algebraic Equations (+/-) (5.6.7)

Solve Algebraic Equations (x/÷) (5.6.8)

Write Variable Expressions - Word Problems (5.6.3)