In Lesson 3-6 you learned about the Addition Property of Equality and the Subtraction Property of Equality. There are properties of equality for multiplication and division as well. One way to solve algebraic equations is to use the Division Property of Equality.
Example
Solve each equation. Check your solution.
Sometimes, you will have to write
and solve an equation to solve a problem.
Example
Consumer Link
4. Xue Wu is
in charge of buying sandwiches for a hiking trip. She has $24, and sandwiches
cost $3.80 each. How many sandwiches can she buy?
Explore You
know that the sandwiches cost $3.80 and Xue Wu
has $24.
Plan Let
s represent the number of sandwiches and write an
equation to represent the problem.
Solve Solve
the equation for s.
Since Xue Wu can’t buy part of a
sandwich, she has
Enough money to buy 6 sandwiches.
Examine Does
the answer make sense?
Round 3.80 to 4 and multiply by 6.
4 × 6 = 24
So 6 sandwiches would cost about
$24. The answer
makes sense.
Another useful property in solving equations is the Multiplication Property of Equality.
Example
Solve each equation. Check your solution.
Example
Geography Link
8. In 1999, Nunavut (NU-na-voot) became Canada’s newest territory in fifty
years. There are 15,000 people in Nunavut under age 25. This is about ⅗ of the total population. What is the population of Nunavut?
Alternative
Solutions :
Let n
represent the total population. Then 
represents the problem.
The total
population of Nunavut is 25,000.
Sumber
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