If m and n are opposite numbers and both are not equal to zero, then x and y are reciprocals of each other. Find xy(m+n)-((m)/(n))+2xy.
若m、n互为相反数且都不等于零，x、y互为倒数．求xy(m+n)-((m)/(n))+2xy．
<gadget id="calculator">1 * 0</gadget>
<output>0</output>

<gadget id="calculator">0 - (-1)</gadget>
<output>1</output>

<gadget id="calculator">2 * 1</gadget>
<output>2</output>

<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<result>3</result>