Calculate how much 15.38-3.99+6.72-9.01=.
计算15.38-3.99+6.72-9.01=多少．
<gadget id="calculator">15.38 - 3.99</gadget>
<output>11.39</output>

<gadget id="calculator">6.72 - 9.01</gadget>
<output>-2.29</output>

<gadget id="calculator">11.39 + (-2.29)</gadget>
<output>9.1</output>

<result>9.1</result>