Math Word Problems: Solving Number Problems Part 1
This is the first post in the Word Problem Solving Series. This series is intended for middle school students. In this post, we are going to discuss how to solve number word problems in Algebra.
The that you should observer in this series translating words into algebraic expressions and equations. Prior to the discussion of word problems, you have already learned how to solve equations, so I will not show the solution in details.
Problem 1
The sum of two numbers is . The larger number is
more than the smaller. What are the two numbers?
Solution
Suppose is a number, the larger number, which is
more than it is
. Therefore, if
a number, then
is the larger number
more than it. If we add the two numbers
the sum is . The sentence “The sum of two numbers is
,” tells us that that the sum
equals
. Therefore, we set up the equation,
.
Simplifying, we have , which gives us
. So, the smaller number is
and the larger number is
.
Checking the Answer
We can check if our solution is correct by verifying the answer. Is the larger number more than the smaller? Yes. Is the sum of the two numbers
. Yes,
. So, we are correct.
Problem 2
One number is twice the other number. Their sum is . What are the two numbers?
Solution
If a number is , twice that number is
. So, if the smaller number in the problem is
, the larger number is
or
. Again in the problem, it says that “their sum is
” which means that if we add
and
, their sum is equal to
.
So, we set up the equation
.
This gives us which gives us
. The larger number is
.
Checking the Answer
Is the larger number twice the smaller? Yes. Is the sum . Yes. Therefore, we are correct.
Problem 3
The sum of three consecutive numbers is . What are the numbers?
Solution
Consecutive numbers are numbers in uninterrupted succession. For example, are five consecutive numbers.
Suppose the consecutive numbers are ,
, and
, we can see that
is the smaller. If
is the smaller, then
is the next number, and
is the largest number. So, if
is the smaller number,
is the next number, and
is the largest number. If we add the three numbers
their sum is . That is,
.
Simplifying, we have . Subtracting 3 from both sides, we have
. Dividing both sides by 3, we have
. So the three consecutive numbers are
,
and
.
Checking the Answer
Are the three numbers consecutive? Yes. Is their sum . Yes,
.
From the worked examples on number problems above, we have learned that the word “is” is most of the time synonymous to the phrase “is equal to.”