Answer:
-27
Step-by-step explanation:
6^2=36
36/-4=-9
36/-2=-18
-9+-18=-9-18=-27
The substance decays by 7.5% every year
n=8
3n-5=19
3n=19+5
3n=24
n=24/3
70%
The answer is 3.
Hope this helps ^^
