90,40,15. What is the next number in the pattern and what is the rule for the pattern

Answer 1

a(n+1)=a(n)/2 -5

a1=90

a2=90/2 -5= 45-5= 40

a3=40/2 -5= 20-5= 15

a4=15/2 -5= 7.5-5= 2.5

The next number is 2.5