$$3.\overline {87} - 2.\overline {59} = ?$$

$$\eqalign{ & 3.\overline {87} - 2.\overline {59} \cr & = \left( {3 + 0.\overline {87} } \right) - \left( {2 + 0.\overline {59} } \right) \cr & = \left( {3 + \frac{{87}}{{99}}} \right) - \left( {2 + \frac{{59}}{{99}}} \right) \cr & = 1 + \left( {\frac{{87}}{{99}} - \frac{{59}}{{99}}} \right) \cr & = 1 + \frac{{28}}{{99}} \cr & = 1.\overline {28} \cr} $$