Help , guide me through this math question

below

step-by-step explanation:

1. 5/1

2. 10/16

3. 90/2

4. 1/20

5. 3/1

6. 14/24

7. 1/4

8. 18/10

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:  

8 < i think

hope this !