A substance has a half-life of 6 years. If 20 pounds are present initially, how much will remain after 2 years?

16.66pound

Step-by-step explanation:

roughly 16.66 pound

if in 6 years it become half which is = 10

then 10:6 = 1.67

then 1.67 pound is decayed every year.

in 2 years it decay 1.67*2 = 3.34

so, the remaining is 20-3.34=16.66pound