It is easy to see how many questions you've asked.
Go to your account page (where you see statistics for your hubs). Click on "Q&A," and you'll see a stats pages for every question you've posted. At the top, it'll list how many questions you've asked, just like your normal stats page will list how many hubs you've written.
As for answers, it's not quite so simple. From the same page, you can click on "Your Answers." This will bring up a news feed of sorts listing out your answers. It looks to me like each page lists 15 answers, and you can click through the pages using the navigational links at the bottom. Figure out how many pages you've got listed, and you can use some simple math to calculate the number of answers you've made. For example, I've got 5 pages of answers. So I must have made somewhere between 60 (15 * 4) and 75 (15 * 5) answers on HubPages.
You'll also get accolades for answering questions. So you'll know when you hit certain benchmarks, like 10, 50, etc.