Same graph for time Series with different intervals?

Hi all, I have two time series (vectors) from the same period of time, but for one observations are for every 5 minutes (A) and the other is for every half an hour (B). First how can I make a line graph that shows both in one graph (while they have different numbers of data based on different intervals). Second:How can I change the A to be identical in number of data as B (in other words converting a 5 minute interval to half an hour interval). And Third, How can I smooth my data, they are places that are too zigzaggy on the graph and I want to smooth it to reduce the noise? Thanks in advance