HELP Enter the exponential function using t (for time) as the independent variable to model the situation. Then
find the value of the function after the given amount of time.
The value of a textbook is $69 and decreases at a rate of 10% per year for 15 years.

The exponential function that models the situation is y=
After 15 years, the value of the textbook is $

i think it is 18

step-by-step explanation:

answer: 0.26

i used the calculator on google

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

source: