Answer:
3.682
Step-by-step explanation:
We don't consider the decimal place or I should say comma so then we read from the first digit as long as it's not zero then until the fourth digit we look at the next digit if it's 5 or greater then we add 1 to the previous digit. And if the next digit is less than 5 then the digit won't change
Alright
so equation is

P=initial amount
and t=time
r=rate
given
initial amount is 50
rate is 10%, but decreasing by 10% so -0.1
and time=6


A(6)=27.4406
about 27mg