A kid goes to a confectionery and buys three kinds of chocolates. The first one is priced at 5 rupees, second one at 3 rupees and third one at 0.5 rupees.

If he bought 100 chocolates in total, how many pieces do you think he bought of each chocolate?

Let us denote the chocolates with a, b and c.
We can frame the following two equations now
a + b + c = 100 ------ (1)
5a + 3b + 0.5c = 100
or 10a + 6b + c = 200 ---- (2)

Now, 2*[(Eq. 2) - (Eq.1)]
9a + 5b = 100
from this equation"a" should be a multiple of 5
for a = 5 ; b = 11
for a = 10 ; b = 2
for a = 15 or more b becomes -ve

Therefore, the two possible answers are
a = 5, b = 11, c = 84
a = 10, b = 2, c = 88

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