Math 7 Unit 5 Lesson 4

Unit 5 Lesson 4

Let's apply what we know about signed numbers to money.

Agenda

• Warm-Up: Activity 4.1

• Activity 4.2: Cafeteria Food Debt

• Activity 4.3: Bank Statement

Warm-Up

Buying Tickets

Multiple Choice

Priya is buying concert tickets for her friends with the money she earns at her part-time job. This month, she has earned $135.

Can she buy three $50 tickets for a concert?

Be prepared to explain why.

Fill in the Blanks

Priya wants to buy 3 tickets for a concert. She has earned $135 and each ticket costs $50. She borrows the rest of the money she needs from a bank and buys the tickets.

How much money will Priya need to borrow from the bank?

Fill in the Blanks

Priya wants to buy 3 tickets for a concert. She has earned $135 and each ticket costs $50. She borrows the rest of the money she needs from a bank and buys the tickets.

How much money will Priya have after she pays the bank back?

Activity 4.2

Cafeteria Food Debt

Cafeteria Food Debt

We are going to answer several questions about Kiran and his Cafeteria Debt. Read the following situation to see where we are starting with Kiran.

At the beginning of the month, Kiran had $24 in his school cafeteria account. Use a variable to represent the unknown quantity in each transaction and write an equation to represent it. Then use a number line.

Multiple Choice

In the first week he spent $16 on lunches. How much was in his account then?

He started with $24 at the beginning of the month.

Which equation best shows the scenario described above?

• -24 + 16 = -8

• 24 + 16 = 40

• 24 + -16 = 8

• -24 + -16 = -40

Fill in the Blanks

Kiran now has $8 in his account. He added some more money and now has $28 in his account.

How much did he deposit in his account?

Fill in the Blanks

He has $28 in his account. He spent $34 on lunches the next week.

How much does he have in his account then?

Fill in the Blanks

He then paid off his debt to the cafeteria.

How much money did he pay?

Open Ended

Why does it make sense to use a negative number to represent Kiran's account balance when he owes money?

Discussion

What do you notice?

What do you wonder?

DEPOSIT

to put money in

WITHDRAWAL

to take money out

Open Ended

If we put withdrawals and deposits in the same column, how can they be represented?

Multiple Choice

Andre withdraws $40 to buy a new music player.

What is his new balance?

**HINT**

To find the starting amount, look at the balance column.

• -$102.47

• -$22.47

• $102.47

• $22.47

Open Ended

If Andre deposits $100 in this account, will he still be in debt? How do you know?

Poll

How do you feel about adding positive and negative integers?