Xiao Ming has 4.2 yuan, and after giving Xiaohu 0.5 yuan, it is 3 yuan more than Xiaohu, so how much money does Xiaohu have.
小明有4.2元钱，给小虎0.5元后，还比小虎多3元，则小虎原有多少元．
<gadget id="calculator">4.2 - 0.5 - 3 - 0.5</gadget>
<output>0.2</output>

<result>0.2</result>