This is a geometric sequence because each term is a common ratio of the previous term. In this case the number of glasses sold in any given hour is 1.2 times the amount sold in the previous hour. This is a geometric sequenc which can always be expressed as:
a(n)=ar^(n-1), a=initial term, r=common ratio, n=term number.
That is the number of glasses sold in any given hour, n. In this case a=10 and r=1.2 so:
a(n)=10(1.2)^(1-n)
She will earn p*a(n) in any given hour, where p is the price which is 1/2 so her revenue, in dollars, in any given hour will be:
r(n)=5(1.2)^(1-n)
