The school built the playground, built all of them on the first day (4/15), built all of them on the second day (3/10), and finished the rest on the third day. How much of the whole work was completed on the third day?
学校修建操场，第一天修建了全部的(4/15)，第二天修建了全部的(3/10)，剩下的第三天修完．第三天修了全部的几分之几？
<gadget id="calculator">4 / 15</gadget>
<output>4/15 = around 0.266667</output>

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

<gadget id="calculator">(4/15) + (3/10)</gadget>
<output>17/30 = around 0.566667</output>

<gadget id="calculator">1 - (17/30)</gadget>
<output>13/30 = around 0.433333</output>

<result>13/30 = around 0.433333</result>