An experienced computer technician can set up a network in 12 hours. it would take an intern 20 hours to set up the same network. if they work together, how long will it take to set up the network?

i need to know how to find the rate that they work

i need to know how long it will take if they work together

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?

The probability that a student graduating from suburban state university has student loans to pay off after graduation is .60. if two students are randomly selected from this university, what is the probability that neither of them has student loans to pay off after graduation?

Luke wants to reduce the area of his rectangular garden by 1/4 the expression 14/w can be used to represent this change. what is another way to write this expression?