fetch and decode operations takes 10 clock cycles
One Byte transfer takes 20 clock cycles
then 64 Bytes takes = 20 * 64 = 1280 clock cycles
Total execution time = 10 + 1280 = 1290 clock cycles
so time require for execution of the instruction is : (1290/10Ghz) sec = (1290 /10 ) * 10-9 sec = 129 nsec