text: need help??? for the five-digit zip code, the first four digits can be any of the digits 0-9 and the fifth any of the digits 1-8. for the plus four zip code, the first three digits can be any of the digits and the fourth any of the digits 1-9. (a). how many possible five-digit zip codes are there? (b). how many possible plus four zip codes are there? (c). how many possibilities are there in all, including both the five-digit zip code and the plus four zip code? a. 10*10*10*10*8=80,000 possible combinations b. 10*10*10*9=9,000 possible combinations c. 18,000*9,000=720,000,000 possible combinations