Answer
a) $b_{n}$ is divergent and $a_{n} > b_{n}$ then $a_{n}$ is divergent as well.
b) $b_{n}$ is divergent and $a_{n} < b_{n}$ then we cannot conclude.
Work Step by Step
a) If a series ($b_{n}$) is cdivergent than we can say that it's sum is infinity. This means a series ($a_{n}$) with a sum bigger than $b_{n}$ will be infinity as well so $a_{n}$ is divergent.
b) If $a_{n}$ is smaller than we cannot conclude anything as it could be any number smaller than infinity (infinity doesn't have an exact value so it is possible for $\infty < \infty$ in a way)
