well, 120,000 has 4 zeros and 12,000 has 3 zeros, so if we divide 120,000 by 10 we get 12,000, just to make it short, 12,000 is one tenth of 120,000 and thus the 10%.
now, 48,000, we know that 120,000 is the 100%, what is 48,000 in percentage off of it?
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} 120000&100\\ 48000&x \end{array}\implies \cfrac{120000}{48000}=\cfrac{100}{x}\implies \cfrac{5}{2}=\cfrac{100}{x} \\\\\\ 5x=200\implies x=\cfrac{200}{5}\implies x=40[/tex]
