There are 78 tons of coal, which have been transported twice, 16 tons each time, how many tons are left undelivered?
有78吨煤，已经运了2次，每次运16吨，还剩多少吨没运？
<gadget id="calculator">16 * 2</gadget>
<output>32</output>

<gadget id="calculator">78 - 32</gadget>
<output>46</output>

<result>46</result>