Yunyun bought a math book with half of the money she saved, and later her sister gave her 5 yuan, and she used 0.4 yuan more than half of the money to buy a foreign language book, and the result was 7.2 yuan left, so she didn’t buy mathematics. How much money is there in total in front of the book?
云云把自己存的钱的一半买了一本数学书，后来姐姐又给她5元，她又用其中比一半多0.4元的钱买了外语书，结果还剩7.2元，那么她未买数学书前共有多少元钱？
<gadget id="calculator">7.2 + 0.4</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>