By 20% decrease in the price of rice, people can buy 10 kg more rice in Rs.100. What is the original price of 1kg of rice?

Rs 2.5

Price = Rs 20 (20% of Rs. 100) Extra rice = 10kg 

Thus, decreased price per kg = \(\frac{20 }{10 }\) = Rs 2

Value of decreased price - 80%

Value of original price - 100%

Therefore, original price per kg = \(\frac{2 }{80 }\) x 100 = Rs. 2.5