How do you determine differences in real world contexts?For example:

An airplane is at 392 feet above sea level. A submarine is at 69 feet below

sea level. How far above the submarine is the airplane?

In this lesson you will learn how to subtract rational

numbers by using real world contexts.

Let’s ReviewLet’s Review

Subtracting means add the additive inverse.4 - (-6) = 4 + (+6) = 10

Let’s ReviewA Common MistakeDoes your answer make sense?

100 feet

0 ft

-25 feet

75 ft ???

100 ft

Let’s ReviewCore Lesson

An airplane is at 392 feet above

sea level. A submarine is at

69 feet below sea level. How far

above the submarine is the

airplane?

392 ft

0 ft

-69 ft

392 - (-69) =

392 + (+69) =461

| 461 | = 461 feet

Let’s ReviewCore Lesson

The temperature at 5pm was -

3°F. It then dropped 15° by 10pm. What was the temperature

at 10pm?

0

-5

-25

5

-20

-15

-10

5pm -3°

Dropped 15°

10pm

-18°

-3-3 + (-15)

= 18-

- 15

In this lesson you have learned how to subtract rational

numbers by using real world contexts.

Let’s ReviewGuided PracticeA hot air balloon was at an elevation of 318 feet. A scuba diver was at 123 feet below sea level. How far above the scuba diver

was the hot air balloon?

Let’s ReviewGuided Practice

A hot air balloon was at an elevation of 318 feet. A scuba diver was at 123 feet below sea level. How far above the scuba diver was the hot air balloon?

318 ft

0 ft

-123 ft

318 - (-123) =

318 + (+123) =441

| 441 | = 441 feet

Let’s ReviewExtension Activities

You overheard a radio announcer report that from 12:00pm to 3:00pm the temperature

went from -5°F to -10°F. He said, “It is getting warmer.” Was he correct? Explain

your reasoning.

Let’s ReviewExtension ActivitiesAn office building in downtown Atlanta has

32 floors above ground. It also has a parking garage with 6 floors below ground for parking. Henry parks on the third floor below ground and works on the 25th floor. Janis works on the top floor and parks on the lowest floor. Albert works on the 15th floor but parks on whatever floor he can.

Continue on next two slides

Let’s ReviewExtension Activities

1.Draw a picture showing the office building and parking garage. But sure to include the floor numbers.

2.How many total floors does the building and parking garage have?

Continued from Previous Slide

Let’s ReviewExtension Activities3. Let’s consider a day of traveling up and down the building

for Henry.a. When Henry arrives to work in the morning, how many

floors does he travel to get to his office?b. Henry decides to go to lunch with Albert. How many

floors does he travel to get to Albert’s office? Which direction did he travel?

c. If Henry drives to lunch, how many floors do they travel from Albert’s office to Henry’s car?

d. Albert and Henry go to lunch and then Henry returns to his office. How many floors in total did Henry travel from the time he left his office to the time he returned back to his office after lunch?

Continued from Previous Slide

Let’s ReviewQuick Quiz

Mt. Everest has an elevation of 29,035 feet above sea level. The Dead Sea has an elevation of 1,348 feet below sea level.

What is the difference in elevation between Mt. Everest and the Dead Sea?

Let’s ReviewQuick Quiz

The temperature on Mars may reach a high of 70°F at the equator in the summer. It may reach a low of -225°F at the poles. Which expression gives the difference between those temperatures?A. 225°F - 70°F B. -70°F + 225°FC. 70°F - 225°F D. 70°F - (-225°F)