give an example of a pair of series $\displaystyle \sum_{}an$ and $\displaystyle \sum_{}bn$ with positive terms where $\displaystyle \lim_{n\to{\infty}}\frac{an}{bn}=0$ and $\displaystyle \sum_{}bn$ diverges, but $\displaystyle \sum_{}an$ converges.

i'm not really sure where to start..please help?