Question

80 members decreased by 65%

Answer 1

There are now 28 members
all you do is 80 times 0.65 = 52
but you still have to subtract 80 - 52 to find the number of members left 
SOOOO
28 members still there 
52 members quit

Answer 2

80 members* (65/100)= 52 members

80 members- 52 members= 28 members

The final answer is 28 members~