Chris has 7 whistles. He needs 10 whistles for party. Which number sentence can help you find how many more whistles Chris needs?
What are your choices?
10 - 7 = ?
To find out how many more whistles Chris needs, you can subtract the number of whistles he already has from the number of whistles he needs for the party. So the number sentence that can help you solve this is:
10 - 7
By subtracting 7 from 10, you will get the result which represents how many more whistles Chris needs for the party.