Xiao Ming brought 20 yuan to buy α pencils, each pencil is 0.8 yuan, how many yuan is left.
小明带了20元准备去买α支铅笔，每支铅笔0.8元，还剩多少元．
<gadget id="calculator">20 - 0.8</gadget>
<output>19.2</output>

<result>19.2</result>