Page 54 - Basic College Mathematics with Early Integers

S E C T ION 1. 4 I SUBTRACTING WHOLE NUMBERS 31

Objective Solving Problems by Subtracting

Often, real-life problems occur that can be solved by subtracting. The first step in Be careful when
solving any word problem is to understand the problem by reading it carefully. solving applications that
Descriptions of problems solved through subtraction may include any of these suggest subtraction. Although
key words or phrases: order does not matter when
adding, order does matter
when subtracting. For exam-
Subtraction
ple, 20 - 15 and 15 - 20
Key Words or Phrases Examples Symbols do not simplify to the same
subtract subtract 5 from 8 8 - 5 number.
difference the difference of 10 and 2 10 - 2
less 17 less 3 17 - 3
less than 2 less than 20 20 - 2
take away 14 take away 9 14 - 9
decreased by 7 decreased by 5 7 - 5
subtracted from 9 subtracted from 12 12 - 9

Concept Check In each of the following problems, identify which number
is the minuend and which number is the subtrahend.
a. What is the result when 6 is subtracted from 40?
b. What is the difference of 15 and 8?
c. Find a number that is 15 fewer than 23.
To solve a word problem that involves subtraction, we first use the facts given to
write a subtraction statement.Then we write the corresponding solution of the real-
life problem. It is sometimes helpful to write the statement in words (brief phrases)
and then translate to numbers.

Example 5 Finding the Radius of a Planet PRACTICE 5
The radius of Jupiter is 43,441 miles. The radius of Saturn is 7257 miles less than The radius of Uranus is 15,759
the radius of Jupiter. Find the radius of Saturn. (Source: National Space Science miles.The radius of Neptune is
Data Center) 458 miles less than the radius of
Uranus.What is the radius of
Neptune? (Source: National
43,441 miles ? Space Science Data Center)

Since subtrac-
Jupiter Saturn tion and addition are reverse
operations, don’t forget that a
subtraction problem can be
Solution: In Words Translate to Numbers checked by adding.
radius of Jupiter ¡ 43,441
- 7257 ¡ - 7257
radius of Saturn ¡ 36,184 Answer
The radius of Saturn is 36,184 miles. 5. 15,301 miles

Work Practice 5 Concept Check Answers
a. minuend: 40; subtrahend: 6
b. minuend: 15; subtrahend: 8
c. minuend: 23; subtrahend: 15