Add 18 to (2/5) of a number, and the sum is 24. Find this number.
一个数的(2/5)加上18，和是24，求这个数．
<gadget id="calculator">24 - 18</gadget>
<output>6</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">6 / (2/5)</gadget>
<output>15</output>

<result>15</result>