Charlie's bag contains 4 blue pens and 3 red pens. He pulls out a pen at random, replaces it in the bag, and then pulls out a second pen at random. If the first pen is blue, what is the probability that the second pen is red

answer: evaluate the objective function at each vertex to determine which - and -values, if any, maximize or minimize the function. example: find the minimum value and maximum value of the objective function f ( x , y ) = 4 x + 5 y , subject to the following constraints