Exercise 2.5 says that the person expects tp save $5000. Is that $5000 in addition to the $10000 savings or does he save the $5000 from from the $10000? This question is not too clear.

My reading is that he has $10K now and expects to save an additional $5K next year.  If that weren't the case, I don't think that the question would make sense.

[NEAS: Correct; the worker expects to save an additional $5,000 next year.]