Question

sara had some 2 rupee and 5 rupee coins in her money box. she exchanged them for some 10 rupee coins. f the number of 5 rupee con is one less than the number of 2 rupee coins, then find the number of 5 rupee coin ​

Answer 1

Answer:

Number of 5 Rs coins =   4  , 14  , 24 .....

10n + 4

Step-by-step explanation:

sara had some 2 rupee and 5 rupee coins in her money box. she exchanged them for some 10 rupee coins. f the number of 5 rupee con is one less than the number of 2 rupee coins, then find the number of 5 rupee coin ​

Let say Number of Coins of Rs 5 = X

Then Number of Coins of Rs 2 = X + 1

Value of 5 Rs coins = 5X

Value of 2 Rs coins = 2X + 2

Total Value = 5X + 2X + 2

7X + 2

Let say Exchanged with Y coins  of Rs 10

Then value of Rs 10 coins = 10Y

7X + 2 = 10 Y

X = 4   Y = 3

X = 14  Y = 10

X = 24  Y = 17

Number of 5 Rs coins =   4  , 14  , 24 .....

10n + 4   where n = 0 , 1 ,.......

Answer 2

Answer:

Let the number of 2-rupee coins be x.

Then, the number of 5-rupee coins will be x - 1

Total amount of 2-rupee coins = ₹2 * x

= ₹2x

Total amount of 5-rupee coins = ₹5 * ( x-1 )

= ₹5x - 5

Total amount in money box = ₹2x + ( ₹5x - 5 )

= ₹ 7x -5

{ if we have to make this amount a multiple of 10 then ₹2 's quantity should be a multiple of 10, and the quantity of ₹5 should be even to be a multiple of 10 }

Therfore, the quantity of ₹2 coins can be 5  (₹2 * 5 = ₹10, a multiple of 10)

and

₹5 coins is 1 less than the quantity of ₹2 coins so

The number of ₹ 5 coins will be  = (5 - 1)

=  4

{ checking, (₹2 * 5) + (₹5 * 4) = ₹10 + ₹20 = ₹30

and ₹ 30 is a multiple of 10 }

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Step-by-step explanation: