EXAMPLE 1 Subtracting Integers

–56 – (–9) = –56 + 9

= –47

–14 – 21 = –14 + (–21)

= –35

Add the opposite of –9.

Add.

Add the opposite of 21.

Add.

a. –56 – (–9)

b. –14 – 21

EXAMPLE 2 Evaluating a Variable Expression

Evaluate 15 – a – b when a = 24 and b = – 36 .

15 – a – b = 15 – 24 – (–36)

= 15 + (–24) + 36

= –9 + 36

= 27

Add the opposite of 24 and of –36.

Add –9 and 36.

Substitute 24 for a and –36 for b.

Add 15 and –24.

EXAMPLE 3 Standardized Test Practice

EXAMPLE 3 Standardized Test Practice

SOLUTION

The height is the difference of the upper and lower elevations.

Vertical height = –600 – (–1200) Write subtraction statement.

= –600 + 1200 Add the opposite of –1200.

= 600 Add

ANSWER The height of the SOFAR channel is 600 meters. The correct answer is C.

GUIDED PRACTICE for Examples 1, 2, and 3

Evaluate the expression.

Add the opposite of 41.

Add.

1. 15 – 41

15 – 41 = 15 + (–41)

= –26

2. –16 – 8

–16 – 8 = –16 + (–8)

= –24

Add the opposite of 8.

Add.

GUIDED PRACTICE for Examples 1, 2, and 3

a – b – (–6) = 8 – (–15) – 6

= 8 + 15 + 6

= 29

Add the opposite of –15 andof –6.

Substitute 8 for a and –15 for b.

Add.

3. a – b – (–6); a = 8, b = –15

GUIDED PRACTICE for Examples 1, 2, and 3

4. Distance What is the difference in elevation between 4 feet above sea level and 30 feet below sea level?

The difference in elevation = 30 feet below sea level + 4 feet above sea level

= 34 ft