This should be easy but....Originally Posted bybharathlece

So you have 100 rs (I assume 100 rupees).

You want to buy 100 balls, consisting of footballs (f), cricket balls (c), and tennis balls (t).

f costs 100rs each.

c costs 1 rupee each.

t costs 0.25 rupee each.

So,

f +c +t = 100 -------------------balls-----(1)

f(15) +c(1) +t(0.25) = 100 -----rupees-----(2)

That is it. No more equation to make from what are given in your question.

So there are 3 unknowns and only two independent equations. Can be solved, maybe, but we need guessing or trial and error.

What if you buy 1 football only?

Then,

f=1

So, c +t = [100-1] = 99 ----(1a)

And, c(1) +t(0.25) = [100 -1(15)] = 85 ----(2a)

c +0.25t = 85 ----(2aa)

From (1a), c = 99 -t. Substitute that into (2aa),

99 -t +0.25t = 85

-t +0.25t = 85 -99

-0.75t = -14

t = -14 / -0.75 = 18.6667 ----not whole number, so not okay.

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What if you buy 2 footballs only?

Then,

f=2

So, c +t = [100-2] = 98 ----(1b)

And, c(1) +t(0.25) = [100 -2(15)] = 70 ----(2b)

c +0.25t = 70 ----(2bb)

From (1b), c = 98 -t. Substitute that into (2bb),

98 -t +0.25t = 70

-t +0.25t = 70 -98

-0.75t = -28

t = -28 / -0.75 = 37.333 ----not whole number again, so not okay.

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What if you buy 3 footballs?

Then,

f=3

So, c +t = [100-3] = 97 ----(1d)

And, c(1) +t(0.25) = [100 -3(15)] = 55 ----(2d)

c +0.25t = 55 ----(2dd)

From (1d), c = 97 -t. Substitute that into (2dd),

97 -t +0.25t = 55

-t +0.25t = 55 -97

-0.75t = -42

t = -42 / -0.75 = 56 ------ping!

Hence, from (1d), c = 97 -56 = 41

Therefore, you can buy 3 footballs, 41 cricket balls and 56 tennis balls. ---answer.

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Check,

f +c +t = 100 -------------------balls-----(1)

3 +41 +56 =? 100

100 =? 100

Yes, so, OK.

f(15) +c(1) +t(0.25) = 100 -----rupees-----(2)

3(15) +41(1) +56(0.25) =? 100

45 +41 14 =? 100

100 =? 100

Yes, so, OK.