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Write equations from word problems

Translates one- and two-step word problems involving whole-number quantities into equations with a letter or symbol representing an unknown, choosing operations that correctly express the relationships among the quantities. The learner interprets the equal sign as equivalence, represents unknowns in different positions, and verifies that a value makes sense in context; formal algebraic manipulation, inequalities, and equations over unrestricted number sets are beyond this scope.

Detailed Explanation: Write equations from word problems

A word problem gives information about quantities and how they are related. To write an equation:

  1. Find the unknown amount.
  2. Choose a letter or symbol for it.
  3. Decide which operations show what happened.
  4. Write an equal sign to show that both sides have the same value.
  5. Check that the answer makes sense in the story.

Example

Maya had 18 stickers. She gave away 7 stickers and then bought some more. Now she has 25 stickers. How many stickers did she buy?

Step 1: Name the unknown.

The number of stickers Maya bought is unknown. Let ss represent that number.

Step 2: Follow the story in order.

  • Maya started with 1818 stickers.
  • She gave away 77, so use subtraction: 18−718-7.
  • She bought ss more, so add ss: 18−7+s18-7+s.
  • The result is 2525, so write =25=25.

The equation is

18−7+s=2518-7+s=25

Step 3: Check the value.

First, 18−7=1118-7=11. Maya had 11 stickers left, so she needed

25−11=1425-11=14

more stickers. Thus, s=14s=14.

Check the equation:

18−7+14=2518-7+14=25

Since both sides equal 25, the equation is correct. Maya bought 14 stickers.

Learn by doing: Write equations from word problems

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    Multiplication Word Problems - Setup (Small Integer Values)

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