Which number is the largest?

How can you find the conditional probability of a given b as the fraction of b’s outcomes that also belong to a, and interpret the answer in terms of the model? i just need a good explanation

In the 30-60-90 triangle below side s has a length of and side r has a length

Apublic library wants to place 4 magazines and 9 books on each display shelf. the expression 4s+9s represents the total number of items that will be displayed on s shelves. simplify the expression