Algebra/Arithmetic/Subtraction Answers

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Problem 1[edit]

You just ordered 100 copies of a best selling book. You've sold 32 copies so far today. Someone calls you on the phone to ask about the book. How many copies should you tell them are left?

Answer

This is a separation type problem:

Number ordered - Number Sold = Number Left

100-32=68

Problem 2[edit]

It is the end of the first day of selling the book. 32 copies were sold in the morning but only 26 copies were sold in the afternoon. How many more copies were sold in the morning than the afternoon?

Answer

This is a comparison type problem:

Greater Number(Morning) - Lesser Number(Afternoon) = Number More

32 - 26 = 6

Challenge: Reword the problem so that the correct answer is -6.

Problem 3[edit]

You received 100 books. You sold 32 copies in the morning and 26 copies in the afternoon. How many books do you left?

Answer

This is a part-whole type problem:

Whole - Part(s) = Number Left

(100 - 32) - 26 = 42

Problem 4[edit]

In between customers you're reading this new best selling book also. The book has 300 pages and today you read 112. How many pages do you need to read tonight if you want to finish the book?

Answer

This is a part-whole type problem:

Pages Total - Pages Read = Pages Left

300 - 112 = 188

Problem 5[edit]

You start the day with 100 books and by the end of the day you have 52 left. How many did you sell?

Answer

This is another part-whole type problem:

Whole - Part = Number missing/sold

100 - 52 = 48