Using an exponential function, it is found that it takes 18.6 days for 80% of the material to decay.
The amount of a substance after t days is modeled by:

In which:
- k is the decay rate, as a decimal.
- A(0) is the initial amount.
The half-life is of 8 days, hence
, and this is used to find k.







Hence:

The time it takes for 80% of the material to decay it t for which
, hence:






It takes 18.6 days for 80% of the material to decay.
To learn more about exponential functions, you can take a look at brainly.com/question/24906920
B= number of beakers which there are 450
t= number of test tubes
the answer is 1.46
I think the answer is plus bc you need to add
Answer: 54
Step-by-step explanation:
63-9 you can't take 9 away from 3 so you must borrow, the 6 becomes a 5 and the 3 becomes 13. 13-9 is 4, bring the 5 down and you have 54.