The total price of the car is $20,000 but each year its price decrese by halve of the catual price, so the first year the new price will be:
![(20000)/(2)=10000](https://img.qammunity.org/2023/formulas/mathematics/college/5v3tn5wdthxkv6typgd7d5s1xssq0uakrn.png)
so he reduce $10,000 dollar, but the next year it cost will decrease halve of the actula price so will be:
![(10000)/(2)=5000](https://img.qammunity.org/2023/formulas/mathematics/college/m1r4s0kyoc17p21g5gtrvgs412j0n25ee5.png)
and is the same with a radiactive element that has 20,000 grams hi will reduce the same amounts, the only diference is that one reduces his mass and the other one reduces his value