given ip is 192.168.16.43/28
scince it is class c ip address and subnating is done with 4 bit
thus
128+64+32+16=240
block size
256-240=16
0    16    32
--    --   --
--    --   -- (and so on)
15    31   47 

Wildcard is always one number less than the block size.In the above instance the block size is 16,the wildcard would be 15.so wild card used for block all the ip address in the ACL is

192.168.16.32 0.0.0.15