Lesson 25: Subtraction Word Problems

New Concept

Formula: Some $-$ Some went away $=$ What is left

What’s next

Next, you'll use this formula to write equations and find the missing piece in different subtraction scenarios.

Property

Some − Some went away = What is left

Examples

• LuAnn had 65 beads and used 13, so she has $65 - 13 = 52$ beads left.
• Celia had 42 shells and 29 are left, so she sent $42 - 29 = 13$ shells away.

Explanation

This is your formula for any 'disappearing act' problem! It connects your starting amount, what went away, and what's left. Use it to find any missing piece by plugging in the two numbers you already know. It's your secret weapon for solving subtraction word problems.

Property

To find the starting amount, solve for the first number in the formula: $p - a = l$.

Examples

• Jaxon gave away 15 pencils and has 22 left. He started with $22 + 15 = 37$ pencils.
• Tamika donated 42 books and has 26 left. She began with $42 + 26 = 68$ books.

Explanation

Forgot how much you started with? Easy fix! Just add the 'went away' amount back to what you have left to find the original total. It’s like reverse-engineering the disappearing act!

Property

To find the amount that 'went away', solve for the middle number: $a - s = l$.

Examples

• Celia had 42 shells and ended with 29. She sent away $42 - 29 = 13$ shells.
• Marko had 42 cards and now has 26. He mailed $42 - 26 = 16$ cards.

Explanation

To figure out how many items vanished, subtract what's left from your starting amount. The difference is the missing 'went away' number. It's a simple subtraction puzzle!