Based on the tree diagram below, what is the probability that a student doesn't have lice, given that the student tested negative? round your answer to the nearest tenth of a percent.

Compare the following pair of numbers a and b in three ways. a. find the ratio of a to b. b. find the ratio of b to a. c. complete the sentence: a is percent of b. a=120 and b=340 a. the ratio of a to b is . b. the ratio of b to a is . c. a is nothing percent of b.