so to start off it would be (1.68)(1)=n(.0821)(158k) ?
Great, now you have n, what do you get from the second sentence, that's different for the first, that you use to solve for the unknown in the second sentence?
Tip: don't neglect units, if they don't match your constant, or what you've given later, you'll have to convert, or you'll never get the answer right. And we don't want to lose any more mars probes, we expect better from scientists.
Reference obscure?