The diameter of number 12 copper wire is 0.081 inches. The maximum safe current it can carry (in order to prevent fire danger in building construction) is 20 A. At this current, what is the drift velocity of the electrons if the number of electron carriers in one cubic centimeter of copper is 8*10^22 ?

Again units conversion. Look up the definition of couloumb and ampere. Similarly, we don't do homework. We help.