Check the picture below.
[tex]p(h)=5000(2)^h\implies \stackrel{p(h)}{100000}~~ = ~~5000(2)^h\implies \cfrac{100000}{5000}=2^h \\\\\\ 20=2^h\implies \log(20)=\log(2^h)\implies \log(20)=h\log(2) \\\\\\ \stackrel{\textit{using the \underline{change of base rule}}}{\cfrac{\log(20)}{\log(2)}=h\implies \log_2(20)=h}\implies 4.3219\approx h[/tex]
