A garage has a letterkeypad lock with the nine letters A,B,C,D,E,F,G,H,I. The keypad can be programmed with a 3 or 6letter code to open the garage. 1. Suppose each letter can be used more than once, how many 3letter codes are possible if: a) there are no restrictions? b) the letters "C" and "D" cannot be used? c) the letter "G" must be used? d) the same letter is not repeated three times? S 2. If each letter cannot be repeated, how many 6-Ietter codes are possible if: a) the letters "C" and "D" cannot be used? S b) the letter "G" must be used? S h c) the order in which the they are entered does not matter? D d) the order of entries does not matter and "H" cannot be used