A garage has a letter-keypad lock with the eight letters A, B,C, D, E, F,G, H. The keypad can be programmed with a 4 or 5-letter code to open the garage. 1. Suppose each letter can be used more than once, how many 4-letter codes are possible if: a) there are no restrictions? 4096 b) the letters "B" and "E" must be used? 1296 () the letter "F" cannot be used? d) the same letter is not repeated four times? 2. If each letter cannot be repeated, how many 5-letter codes are possible if: a) the letters "B" and "E" must be used? b) the letter "F" cannot be used? c) the order in which the they are entered does not matter? d) the order of entries does not matter and "H" cannot be used