what is the value of the expression 2a to the power of 3 if a=4?

what is the value of the expression 2a to the power of 3 if a=4? 

If a=4, then 2a means 24

24^3=13,824

We either have

(2a)³  = (2[4])³  = 8³  = 512

Or

2a³  = 2(4)³   = 2(64)  =  128