Solving a Problem Involving SubtractionThe record-high temperature in the United States is 134°F, recorded at Death Valley,
California, in 1913. The record low is 80°F, at Prospect Creek, Alaska, in 1971. See
FIGURE 16. What is the difference between these highest
and lowest temperatures? (Source: National Climatic
Data Center.)
We must subtract the lowest temperature from the
highest temperature.
Definition of subtraction= 214 Add.
= 134 + 80
134 - 1 - 802
-
EXAMPLE 10
SECTION 1.5 Adding and Subtracting Real Numbers 43
NOW TRY
EXERCISE 10
Find the difference between a
gain of 226 yd on the football
field by the Chesterfield
Bears and a loss of 7 yd by
the New London Wildcats.
NOW TRY ANSWERS
10.233 yd
Order of
numbers
matters in
subtraction.134 °–80°Difference is
0 °^134 ° – (– 80°).FIGURE 16The difference between the two temperatures is 214°F.
NOW TRYOBJECTIVE 6 Use signed numbers to interpret data.
Using a Signed Number to Interpret DataThe bar graph in FIGURE 17gives the Consumer Price Index (CPI) for footwear be-
tween 2002 and 2007.
NOW TRY EXAMPLE 11
EXERCISE 11
Refer to FIGURE 17and use a
signed number to represent
the change in the CPI from
2003 to 2004.
YearFootwearSource: U.S. Bureau of Labor Statistics.Consumer Price Index (CPI)^01101151201251302002 2003 2004 2005 2006 2007119.3 119.6121.4 122.6 123.5 122.4FIGURE 1711.0.3
(a)Use a signed number to represent the change in the CPI from 2005 to 2006.
Start with the index number for 2006. Subtract from it the index number for
2005.
123.5 122.6
2006 index 2005 index A positive number
indicates an increase.(b)Use a signed number to represent the change in the CPI from 2006 to 2007.
122.4 123.5
2007 index 2006 index A negative number
indicates a decrease.
NOW TRY