A piece of cake is eaten by four people, A and B have eaten (1/10) of this piece of cake, C has eaten (2/10), and D has eaten (3/10), what fraction of this piece of cake is left?
一块饼四个人吃，甲乙都吃了这块饼的(1/10)，丙吃了(2/10)，丁吃了(3/10)，这块饼还剩下几分之几？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">1 - (1/10) - (1/10) - (1/5) - (3/10)</gadget>
<output>3/10 = around 0.3</output>

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