Can someone me solve #35 #37 and number #39 even if you solve one that is fine

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

The random variable x is the number of occurrences of an event over an interval of ten minutes. it can be assumed that the probability of an occurrence is the same in any two-time periods of an equal length. it is known that the mean number of occurrences in ten minutes is 5.3. the appropriate probability distribution for the random variable

Sum is 17 and their difference is 3