Xiaojuan bought a science and technology book with half of the money she saved, and then her mother gave her another 5 yuan, and she bought a dictionary with 0.4 yuan more than half of it, and the result was 7.2 yuan left, so how much did Xiaojuan save? Yuan money.
小娟用自己存的钱的一半买了一本科技书，后来妈妈又给她5元，她又用其中的一半多0.4元买了字典，结果还剩7.2元，那么小娟原来存了多少元钱．
<gadget id="calculator">0.4 + 7.2</gadget>
<output>7.6</output>

<gadget id="calculator">7.6 * 2</gadget>
<output>15.2</output>

<gadget id="calculator">15.2 - 5</gadget>
<output>10.2</output>

<gadget id="calculator">10.2 * 2</gadget>
<output>20.4</output>

<result>20.4</result>