Does anyone anything about depreciation in finance?

Question

I have this maths question it is:

Find the value of a $900 washing machine in 15 years time if it depriciates by 20% on a reducing balance

Does anyone know the answer, or even better know how to work out this question. My parents wont help and I have no idea what to do. Even a website that can explain how to do this sort of question would be helpful

Answer 1

Reducing balance is that is reduces by 20% each year so the equation is

Value = 900 (0.80)^t where t is the number of years

So after 15 years, the value of the washing machine is
= 900 (0.80)^15
= 900(0.03518)
= 31.67

So the washing machine is worth $31.67 after 15 years.

Answer 2

If it depreciates 20% per year its value each year is 80% of the previous year's value, and the value after 15 years will be
V = 900*0.8^15

Answer 3

http://en.wikipedia.org/wiki/Depreciation