Find the unknown: (2013/2014)*2015=(2013/2014)+x.
求未知数：(2013/2014)*2015=(2013/2014)+x．
<gadget id="calculator">2_013 / 2_014</gadget>
<output>2_013/2_014 = around 0.999503</output>

<gadget id="calculator">(2_013/2_014) * 2_015</gadget>
<output>4_056_195/2_014 = around 2_013.999503</output>

<gadget id="calculator">(4_056_195/2_014) - (2_013/2_014)</gadget>
<output>2_013</output>

<result>2_013</result>