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Linear and Quadratic Equations · Question 29 of 66

Question 29

EasyOriginal question

Lalremsiami has 30 coins, all of them ₹2 or ₹5 coins, worth ₹99 altogether. How many ₹5 coins does she have?

13Correct answerYour answer17Correct answerYour answer33Correct answerYour answer39Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

Let there be $f$ coins of ₹5, so $30 - f$ coins of ₹2.
Value: $5f + 2(30 - f) = 99$ , so $3f + 60 = 99$ .
$3f = 39$ , giving $f = 13$ . (Check: $65 + 34 = 99$ .)

Worth noting

17 is the number of ₹2 coins. 39 is $3f$ , not $f$ .

Concept: Coin problem: count equation and value equation
Typical timeTypical: 40 s
Your timeYours: —

The rule this testsWord problems into equations

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