80 members decreased by 65% percent of change

28 members

Explanation:

If there is a decrease of 65%, it means that 100%-65%=35% of the members are left.

So we just need to find 35% of 80.

35100*80=28 members.

The other way is to find the actual decrease, which is:

65100*80=52 members

80-52=28 members remain.