Problem: A computer system uses passwords that contain exactly.r eight characters, and each character is 1 of the 25 lowercase letters (a-z} or 26 uppercase letters {t-Z) or 1t] integers {t}- 9}. Let H denote the set of all possible passwords. and let A and 3 denote the events that consist of passwords with only:r letters or only integers, respectively. Determine the number oi passwords in each of the following events (3} 0 (b) a {c} #0 B' (d) Passwords that contain at least 1 integer to) Passwords that contain exactlv 1 integer Please explain it needed, so I can understand it. Thank you