At the begining of the month, Evan had $24 in his account at the school bookstore. Use a variable to represent the unknow quantity on a number line. What is the unkown quantity in each case?
First he bought some notebooks and pens that cost $16.
Then he deposited some more money and his account balance was $28.
Then he brought a book for English class that costs $34.
Then he deposited exactly enough money so that he paid off his debt to the bookstore.
Explain why it makes sense to use a negative number to represent Ecan's account balance when he owes money.
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