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Word Problems Into Equations: Tiles, Parties And Savings

Choose an unknown, write an equation from a real situation, solve it, and answer in words; solve bracketed equations in more than one way.

8 micro-lessons

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Four Steps for Word Problems

Choose the unknown, write the equation, solve, answer in words.

From a story to an answer (Textbook pp. 174–177)

Decide what the unknown is, and give it a letter.
Write each quantity using that letter.
Use what is equal in the story to write an equation.
Solve, check, and answer the question that was asked, with units.

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Ranjana's Tile Pattern

Example 7: can the T-shaped pattern use exactly 100 tiles?

Problem. Ranjana's tile arrangements grow step by step. Can she make one with 100 tiles? Which step? (Textbook p. 174)

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Madhubanti's Chaat Party

A party with plates of chaat delivered from the town shop.

A delivery boy hands covered plates of chaat to a girl at her door while family and friends sit inside on a durrie.

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Each plate costs ₹25, delivery costs ₹50, and Madhubanti can spend ₹500. How many friends can she invite?

The Party and the Savings

Examples 8 and 9, each solved with an equation.

Problem 1 (Example 8, p. 175). Each plate of snacks costs ₹25 and delivery costs ₹50. Madhubanti can spend ₹500. There are 5 people in her family, including her. How many friends can she invite, with one plate per person?

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Money and Patterns

Set up and solve word problems.

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A taxi costs ₹800 a day plus ₹20 per km. The total is ₹2200. How many km? (p. 186, Q6)

Equations with Brackets

Undo the outside first, or expand first; both work.

Choices (Textbook p. 177)

For an equation like 28(x + 4) + 300 = 1000 you can:

(a) remove +300, then divide by 28, then subtract 4;
(b) notice 28, 300 and 1000 are all divisible by 4, and divide every term by 4 first;
(c) expand the bracket first.

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Three Ways to Solve Example 10

Solving 28(x + 4) + 300 = 1000 three ways.

Problem. Solve 28(x + 4) + 300 = 1000. (Textbook p. 177)

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