One piece of wood, Master Li used up (2/5) to make a table and (3/10) to make a bench, have you used up this piece of wood? What fraction is left?
一根木料，李师傅做桌子用去了(2/5)，做板凳用去了(3/10)，这根木料有没有用完？还剩下几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(2/5) + (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>