If `10%` of a number x is 25, then find the value of `20%` of x.

If 20% of x+40% of (x)/(2)+20% of 3x=100 , then find the value of x.

If 10% of x is equal to 20% of y, then find x:y.

The present value of a car is Rs. 360000. If the value of the car decreases at the rate of 10% in the first year and in the next every year the rate of decrease is 20% per year. Then find the value of car after 3 years.

If 10% of x = 20% of y, then x: y is equal to :