A piece of rope was used for the first time (1/8), and for the second time (3/8), how much was used for the two times? What fraction is left?
一条绳子，第一次用去了(1/8)，第二次用去了(3/8)，两次一共用去了几分之几？还剩几分之几？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">(1/8) + (3/8)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>