a) How many plates are possible when letters and numbers can repeat? Set up the expression that can be used to calculate the number of plates that are possible when letters and numbers can repeat.The expression is. ___ (Do not simplify.)The number of plates possible when letters and numbers can repeat is. ___(Use scientific notation. Use the multiplication symbol in the math palette as needed. Round to three decimal places as needed.)b) How many plates would be possible if letters could repeat but numbers could not? ___(Use scientific notation. Use the multiplication symbol in the math palette as needed. Round to three decimal places as needed.).c) How many plates would be possible if letters could not repeat but numbers could? ___(Use scientific notation. Use the multiplication symbol in the math palette as needed. Round to three decimal places as needed.)d) How many plates would be possible if neither letters nor numbers could repeat? ___(Use scientific notation. Use the multiplication symbol in the math palette as needed. Round to three decimal places as needed.)e) What is the probability that a randomly generated plate has no repeating letters or numbers? ___(Type an integer or decimal rounded to three decimal places as needed.)