Idea 19of 23Builds onUndo a take-awaySolve it on the balance
An equation from a story
How do you write and solve an equation for a story?
Today you'll discover
- how the story becomes 4p + 3 = 31
- how to solve it
- how to check it against the story
Think first4 packs of pens and 3 loose: 31 pens
Which equation fits the story?
Decide first, then press Next. Match each number in the story to a part of the bar.
A bar of 31 pens over four equal pieces marked p and a small piece of 3. Then the equation 4p + 3 = 31, the working 4p = 31 − 3 = 28, so p = 28 ÷ 4 = 7, and the pieces filled with 7 and the check 4 × 7 + 3 = 31. The last step shows a bar of $39 over five pieces marked t and a $4 piece.
See the whole ideathe big idea and the key word, in one place
The big idea
Write the story as an equation, solve it, and check the answer in the story.
Story to answer
Four steps, every time.
- story4 packs, 3 loose, 31
- equation4p + 3 = 31
- solvep = 7
- check4 × 7 + 3 = 31
Easy to get wrongAsk whether the answer makes sense: 7 pens in a pack fits the story; 28 pens in a pack would not.
Key word
- model
- an equation or drawing that shows how the numbers in a story fit together
Ready to use it?
- Write an equation for a story and solve it.