Question

pls help maths question

Answer 1

Solution:


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Given:


Condition 1 : Kashish had a total of Rs. 40 in coins of denomination Rs.10, Rs.5 and Rs.2 respectively,.

Let the number of Rs.10 coins be x,.
Let the number of Rs.2 coins be y.,
Let the number of Rs.5 coins be z.,

Hence,

=> 10x + 2y + 5z = 40      ..(i)

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Condition 2: The ratio of number of Rs.10 coin and Rs. 5 coin is 1:2,
then,.

=> 2x = z,.

So, if we modify (i),
 we get,.

=> 10x + 2y + 5(2x) = 40,.

=> 10x+2y+10x = 40,.

=> 20x+2y= 40,.

=> 10x+y = 20,..  ..(ii)

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Condition 3 : She had a total of 13 coins,.
then,.

=> x + y + z = 13,.

=> x + y + 2x = 13,.

=> 3x + y = 13,..    ..(iii)

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(ii) - (iii) => 10x + y -(3x + y) = 20 -13

                    10x + y - 3x - y = 7

                                         7x = 7

                                           x = 1..

         ∴   The number of Rs.10 coins she had is 1,.

As, number of Rs. 5 coins she had is double the amount of Rs.10 coins she had,
Hence,.

=> 2x = z,

=> 2(1) = z


=> z = 2,

She had 2 Rs.5 coins,.
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(ii)=> 3x+y = 13

=> 3(1)+y = 13,

=> 3+y = 13

=> y = 13 - 3

=> y =10,..

 ∴ She had 10 Rs. 2 coins,..

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                           Hope it Helps!!