Whats the answer for number 12? Thank you!

Simplify (a/b - b/a) times (a - a^2/a+b) a - a^2/a=b is a mixed number

Julian wrote the following numeric pattern on the board3,10,17,24,31,38.what numbers of julian's pattern are compound numbers.

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?