Final answer:
In summary, the code needed would calculate the last index of 'a' being 13, find the length of string x as 15, and use these values to compute the result as p = (15^13) / 54. This is based on an understanding of the provided solution although it doesn't address the power computation exactly as described.
Step-by-step explanation:
The question pertains to a programming scenario where a student is required to find the last index of the character 'a' in a string at position 13, determine the length of the string, and then calculate the value of the power of the index over the length of the string. We start by assuming that the length of string x is given to be 15 (as per the provided calculations in Solution 8.13 that x = 13 + 2 = 15). We're also given n = 50 + 4 = 54 which would be the length of the sequence or the string. The calculation would involve raising the index (13) to the power of the length of x (15) and taking the result over the length of the sequence (54), which is mathematically denoted as p = (15^13) / 54. However, this p value calculation seems different than what is provided in the existing solution, which calculates the ratio differently (15/54).