Answer:
Hello!
To answer your question:
8% of 23,400 is 1872.
23,400- 1872= $21,528 by the end of the first year
1 year=12 months
1872/12= $156- this is how much it is decreased monthly.
156 is 0.67% of 23400, so the monthly percent decrease of 0.67%.
Hope this helps, and hope this is right! :)