their income is "x", which oddly enough is the 100% of their income, we also know that 16% of it 240 bucks, so
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} x&100\\ 240&16 \end{array}\implies \cfrac{x}{240}=\cfrac{100}{16}\implies 16x=24000 \\\\\\ x=\cfrac{24000}{16}\implies x=1500[/tex]
