Bob climbed down a ladder from his roof, while roy climbed up another ladder next to him. each ladder had 30 rungs. bob went down 2 rungs every second. roy went up 1 rung every second. a- let statement b- system of equations c-at some points , bob and roy were at the same height. which rung were they on ?

Quick! a survey of 57 customers was taken at a bookstore regarding the types of books purchased. the survey found that 33 customers purchased mysteries, 25 purchased science fiction, 18 purchased romance novels, 12 purchased mysteries and science fiction, 9 purchased mysteries and romance novels, 6 purchased science fiction and romance novels, and 2 purchased all three types of books. a) how many of the customers surveyed purchased only mysteries? b) how many purchased mysteries and science fiction, but not romance novels? c) how many purchased mysteries or science fiction? d) how many purchased mysteries or science fiction, but not romance novels? e) how many purchased exactly two types of books?