Xiao Ming bought 10 exercise books and 10 pencils for 19 yuan, and he still has money left. If you want to buy a pencil, you will pay 0.3 yuan more; if you buy another exercise book, you will lose 0.2 yuan. How much is Xiao Ming originally?
小明花19元买了10本练习本和10支铅笔，他还有余钱．如果要买1支铅笔，就多0.3元；如果再买一本练习本就少0.2元．小明原有多少元．
<gadget id="calculator">0.3 + 0.2</gadget>
<output>0.5</output>

<gadget id="calculator">10 * 0.5</gadget>
<output>5</output>

<gadget id="calculator">19 - 5</gadget>
<output>14</output>

<gadget id="calculator">14 / 2 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">19 + (7/10) + 0.3</gadget>
<output>20</output>

<result>20</result>