7th Grade Unit 1A Review

Which of the following statements BEST describes a situation in which opposite quantities combine to make zero?

• Pepper baked 12 cookies, and put each cookie in an individual bag.

   

• Lola received $20 from her grandma and another $20 from her grandpa.

• A climber ascended 100 feet and then descended 100 feet.

• Bronson loses his wallet, which contained $50.

Answer explanation

Ascending 100 feet would put you at a positive 100 feet elevation. Descending 100 feet (-100) would bring you back down to 0.

100 + -100 =0

What is the sum of –7.2 + 9.9 + –4.5?

• –21.6

• –1.8

• 1.8

• 21.6

Answer explanation

-7.2 + 9.9 = 2.7

2.7 + (-4.5)= -1.8

At 4:00 a.m., the temperature outside was 12°F below zero. By noon, it rose by 15°F.  At 6:00 p.m., the temperature dropped by 7°F. What was the evening temperature?

• –34°F

• -4°F

• 10°F

• 34°F

Answer explanation

12F below zero is -12F. Since the temperature rose 15F, we would add -12+ 15 to get 3F. Then, since the temperature dropped 7F, we would add

3F+(-7F) to get -4F.

Lindsay is competing on Jeopardy. She begins with an initial score of 150 points but loses 500 points throughout the game. She represents her score using the expression shown?

150 – 500

Which of the following expressions also represents Lindsay’s Jeopardy score?

• 500 – (–150)

• 150 + 500

• 150 + (–500)

• –500 – 150

Answer explanation

We can change 150 - 500 into an addition problem by adding the additive inverse.

So 150 - 500 would be

150 + (-500)

They would also yield the same answer.

Lola owes Andy $2, and Andy owes Lola $5. Which of the following statements means the same thing?

• Lola owes Andy $3.

• Lola owes Andy $7.

• Andy owes Lola $3.

• Andy owes Lola $7.

Answer explanation

Lola owes Andy $2, but since Andy also owes Lola $5, we can set this up as

-5 + 2 = -3, meaning Andy still owes Lola 3 dollars.

Mari had $237.60 in her checking account at the beginning of the week. Over the next three days, she withdrew $5.50 on Monday, deposited $20.67 on Tuesday, and withdrew $100.25 on Wednesday. How much money was in her bank account at the end of Wednesday?

Answer explanation

Withdraw means taking money out of her account, so it would be represented as a negative number. Deposit mean putting money into the account, so it would be represented as a positive number. Your equation is:

$237.60 + (-$5.50) + $20.67 + (-$100.25)

Answer: $152.52

• 1

• 1

Answer explanation

-4/5 and 4/5 are additive inverses, so when you sum them up, they equal zero.

Answer explanation

-8.1

First we have to change the equation into an addition problem using additive inverse.

5 2/9 + (-8.1) + (-5 2/9)

Then you can use communitive property to simplify.

5 2/9 + (-5 2/9) + (-8.1)

5 2/9 + (-5 2/9) = 0, so 0 + (-8.1)= -8.1

Answer explanation

We can use communitive and the associative property to simplify:

-1/2 + 1/2 + 7 + 3

0 + 7 + 3 = 10

Which point on the number line represents 2 more than 5? How do you know?

• A

• B

• C

• D

Answer explanation

2 more than 5 is 5 + 2, which is 7.