At present the sum of the number of students in all M.S.K in a district is 3993. If the number of students increased in a year was 10% of its previous year, let us calculate the sum of the number of students 3 years before in all the M.S.K in the district.

Three years before from today a family had planned to reduced the expenditure of electric bill by 5% in comparison to its previous year. 3 year before, that family had to spend ₹4000 in a year for electric bill. Let us write by calculating how much amount will the family have to spend to pay the electric bill in the present year.

Weight of Savan babu is 80kg. In order to reduces his weight, he started regular morning walk. He decided to reduce his weight every year by 10%. Let us write by calculating, his weight after 3 years.

As the farmers are becoming more alert of the harmful effects of applying only the chemical fertilisers and insecticides in agricultural lands, the number of farmers using fertilisers and insecticides in village of Rasulpur decreases by 20% in a year in comparison to its previous year. Three years before, the number of such farmers was 3000, let us calculate the number of such farmers in that village now.

The price of a machine of a factory is ₹18000. The price of that machine decreases by 10% in each year. Let us calculate its price after 3 years.