Question

a man buys postage stamps of denominations 3 paise and 5 paise gor rupees 1.00 he buys 22 stamps in all find the number of 3 paise stamps bought by him

Answer 1

p+q=22p+q=22

and

3p+5q=1003p+5q=100 (yes, because 1 Rs. = 100 paise! and not other way round)

where, pp is the number of 3 paise stamps and qq is the number of 5 paise stamps.

Thats, 2 equation and 2 unknown, how hard is that?