Priya wants to buy 3 tickets for a concert. Each ticket costs $50. She has earned $135.
What could Priya do in order to be able to buy the tickets?
One equation that represents this situation is . What do each of the numbers tell us about this situation?
Another equation that represents this situation is . What do each of the numbers tell us in this situation?
8.2
Activity
Earning and Spending
For each transaction:
Use a variable to represent the unknown quantity, and write an equation.
Represent the transaction on a number line.
Find the unknown quantity.
At the beginning of the month Kiran had $24. He spent $16 at a craft fair. How much money did he have then?
After he earned some money babysitting, he had a total of $28. How much did he earn?
Then he pledged to donate $30 to the local animal shelter. Kiran said, “Uh oh. Now I have -$2.” What do you think he meant by that?
Kiran spent $5 on supplies to clean windows. How much money would he say he had after that?
Kiran washed some windows and earned enough money so that now he can pay off his pledge. How much money did he earn?
8.3
Activity
Bank Statement
Here is a bank statement.
A checking account statement for Andre person. A 5-column table shows the activity in his account for the month of October. Column 1 is labeled “Date,” column 2 is labeled “Description,” column 3 is labeled “Withdrawals,” column 4 is labeled “Deposits,” and column 5 is labeled “Balance.” There are 8 rows describing each transaction Andre made with the bank. Row 1: Date: 10, 3, 2017; Description, Previous balance; Withdrawals, blank; Deposits, blank; Balance, 39 point 8 7 dollars. Row 2: Date: 10, 5, 2017; Description, Check Number 256; Withdrawal, 28 point 5 0 dollars; Deposits, blank; Balance, 11 point 37 dollars. Row 3: Date: 10, 6, 2017; Description, A T M deposit – Cash; Withdrawals, blank; Deposit, 45 point 0 0 dollars; Balance, 56 point 3 7 dollars. Row 4: Date: 10, 10, 2017; Description, Wire transfer; Withdrawals, 37 point 9 1 dollars; Deposits, blank; Balance: 18 point 4 6 dollars. Row 5: Date: 10, 17, 2017; Description, Point of Sale Grocert Store; Withdrawals, 16 point 4 3 dollars. Deposits, blank; Balance, 2 point 0 3 dollars. Row 6: Date: 10, 25, 2017; Description, Funds Transfer from Savings; Withdrawals, blank; Deposits, 50 point 0 0 dollars; Balance, 52 point 0 3 dollars. Row 7: Date: 10, 28, 2017; Description, Check Number 257; Withdrawals, 42 point 0 0 dollars; Deposits, blank; Balance, 10 point 0 3 dollars. Row 8: Date 10, 29, 2017; Description, Online Payment Phone Services; Withdrawals, 72 point 5 0 dollars; Deposits, blank; Balance, negative 62 point 4 7 dollars.
Andre makes a withdrawal of $40 to buy a music player. What is his new balance?
If Andre makes a deposit of $100 into this account, will he still be in debt? Explain your reasoning.
If withdrawals and deposits were in the same column, how could each be represented using signed numbers?
Student Lesson Summary
Banks use positive numbers to represent money that gets put into an account and negative numbers to represent money that gets taken out of an account. When money is put into an account, it is called a deposit. When money is taken out of an account, it is called a withdrawal.
People also use negative numbers to represent debt. If we take out more money from our account than we put in, then we owe the bank money, and our account balance will be a negative number to represent that debt. For example, if we had $200 in our bank account, and then we wrote a check for $300, we would owe the bank $100, and our account balance would be -$100.
starting balance
deposits and withdrawals
new balance
0
50
50
150
200
-300
-100
In general, we can find a new account balance by adding the value of the deposit or withdrawal to it. We can also tell how much money is needed to repay a debt using the fact that to get from a value to 0, we need to add its opposite.
Glossary
deposit
A deposit is when money is put into an account.
For example, a person added $60 to their bank account. Before the deposit, they had $435. After the deposit, they had $495, because .
withdrawal
A withdrawal is when money is taken out of an account.
For example, a person took out $25 from their bank account. Before the withdrawal, they had $350. After the withdrawal, they had $325, because .
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