The arrangement of data is like this:
1st c-bytes in 1st block
Next c-bytes in 2nd block
And so on.
--------------------------------------------
cache block size = 128 B
main memory = k banks
In single iteration we can access:
k*c bytes
= 24*2
= 48B
for which we require 80ns.
Also, time required for decoding in single iteration
= K/2ns
= 24/2
= 12ns
so here we require 3 access to fetch 128 bytes
So, total time = 3*( 80 +12 ) = 276 ns