# Lesson 7

Changing Elevation

### Problem 1

What is the final elevation if

1. A bird starts at 20 m and changes 16 m?
2. A butterfly starts at 20 m and changes -16 m?
3. A diver starts at 5 m and changes -16 m?
4. A whale starts at -9 m and changes 11 m?
5. A fish starts at -9 meters and changes -11 meters?

### Solution

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### Problem 2

One of the particles in an atom is called an electron. It has a charge of -1. Another particle in an atom is a proton. It has charge of +1. The charge of an atom is the sum of the charges of the electrons and the protons. A carbon atom has an overall charge of 0, because it has 6 electrons and 6 protons and $$\text- 6 + 6 = 0$$. Find the overall charge for the rest of the elements on the list.

charge from
electrons
charge from
protons
overall
charge
carbon -6 +6 0
neon -10 +10
oxide -10 +8
copper -27 +29
tin -50 +50

### Solution

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### Problem 3

Add.

$$14.7 +28.9$$

$$\text-9.2 + 4.4$$

$$\text-81.4 + (\text-12)$$

$$51.8 + (\text-0.8)$$

### Solution

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### Problem 4

Select all the true statements.

A:

$$\text-5 < |\text-5|$$

B:

$$|\text-6| < \text-5$$

C:

$$|\text-6| < 3$$

D:

$$4 < |\text-7|$$

E:

$$|\text-7| < |\text-8|$$

### Solution

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(From Unit 7, Lesson 5.)

### Problem 5

Last week, the price, in dollars, of a gallon of gasoline was $$g$$. This week, the price of gasoline per gallon increased by 5%. Which expressions represent this week's price, in dollars, of a gallon of gasoline? Select all that apply.

A:

$$g + 0.05$$

B:

$$g + 0.05g$$

C:

$$1.05g$$

D:

$$0.05g$$

E:

$$(1+0.05)g$$

### Solution

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(From Unit 6, Lesson 5.)

### Problem 6

A family goes to a restaurant. When the bill comes, this is printed at the bottom of it:

 Gratuity Guide For Your Convenience: 15% would be $4.89 18% would be$5.87 20% would be \$6.52

How much was the price of the meal? Explain your reasoning.

### Solution

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(From Unit 6, Lesson 7.)