The sum of 3 times of a number plus 0.9 is 1.5, what is the half of the number.
一个数的3倍加上0.9的和是1.5，这个数的一半是多少．
<gadget id="calculator">1.5 - 0.9</gadget>
<output>0.6</output>

<gadget id="calculator">0.6 / 3 / 2</gadget>
<output>0.1</output>

<result>0.1</result>