well, let's take a looksie, if it decreased by 50% the 1st year, that means what's leftover is 50% of it, well
[tex]\begin{array}{|c|ll} \cline{1-1} \textit{a\% of b}\\ \cline{1-1} \\ \left( \cfrac{a}{100} \right)\cdot b \\\\ \cline{1-1} \end{array}~\hspace{5em}\stackrel{\textit{50\% of 10000}}{\left( \cfrac{50}{100} \right)10000}\implies 5000[/tex]
so, on the next year it increases by 60% of 5000
[tex]\begin{array}{|c|ll} \cline{1-1} \textit{a\% of b}\\ \cline{1-1} \\ \left( \cfrac{a}{100} \right)\cdot b \\\\ \cline{1-1} \end{array}~\hspace{5em}\stackrel{\textit{60\% of 5000}}{\left( \cfrac{60}{100} \right)5000}\implies 3000~\hfill \underset{current~value}{\stackrel{5000~~ + ~~3000}{8000}}[/tex]
well, 10% of 10000 is 1000 bucks, if the consultant is correct, I should have 10000 + 1000 = 11000, but I don't, so he needs a nice cup of tea and chill some.
well, I started with 10000 bucks, now I only have 8000, lost 2000 bucks, 2000 is 1/5 of 10000 or namely 20%.