Please answer all parts of the question

20. Suppose n - pqr is the product of three distinct primes. How would an RSA-type scheme work in this case? In particular, what relation would e and d satisfy? Note: There does not seem to be any advantage in using three primes instead of two. The running times of some factorization methods de- pend on the size of the smallest prime factor. Therefore, if three primes are used, the size of rn must be increased in order to achieve the same level of security as obtained with two primes