Review: Finding The Unknown — Ganita Prakash: Class 7 Mathematics, Part 2 (NCERT)

What You Can Do Now

Tick what you can now do with equations.

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After this chapter, I can…

Chapter in One Card

The key ideas at a glance.

Finding the unknown (Textbook p. 190)

An equation says that two algebraic expressions are equal.

Doing the same operation to both sides keeps the equality.

A solution is a value of the unknown that makes LHS = RHS.

Solve by doing the same thing to both sides until the unknown stands alone. Then check.

Key Terms From This Chapter

Flip through the chapter's words and moves.

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Questions From the Whole Chapter

Eight questions from quick recall to harder reasoning.

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Solve x + 9 = 4.

Step-by-Step Challenge Problems

Three word problems with guided steps.

Plan, solve and check

For each problem: say what the unknown is, write the equation, solve it, check it, and answer in words.

An autorickshaw charges ₹30 plus ₹15 per km. A ride costs ₹180. How far was it?
Asha has ₹1200 and saves ₹150 a month. Bina has ₹2000 and saves ₹50 a month. After how many months will they have the same amount?
Hens and goats in a yard have 20 heads and 56 legs. How many of each?

Unknown, equation, solution, check, answer

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Solve It Yourself

Four problems from the chapter, no hints.

Solve each problem

Solve 4(m + 6) − 8 = 2m − 4, and check your answer. (Textbook p. 172)
In Ranjana's tile pattern, Step k uses 3k + 1 tiles. Which step uses exactly 100 tiles? (p. 174)
A fruit juice costs ₹15 less than a milkshake. 4 juices and 7 milkshakes cost ₹600. Find both prices. (p. 187)
Explain with x why the magic trick (× 2, + 10, ÷ 2, subtract your number, + 3) always gives 8. (p. 190)

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Talk it through: equation doubts

Stuck on a step? Ask here.

Learners can ask follow-up questions and keep the thread going.

Ask me about anything in this chapter: why doing the same thing to both sides keeps an equation true, why a term changes sign when it moves, brackets with a minus in front, the difference between 'no solution' and the solution 0, how to choose the unknown in a word problem, or Brahmagupta's formula. Tell me the equation or problem and the step where you're stuck.

almost 3 years ago