A pile of coal was brought in from the school cafeteria. It was planned to burn 50 kilograms of coal every day, and it took 6.5 days to burn it out, but it took 10 days to actually burn it out. How many kilograms of coal is actually burned less than planned every day?
学校食堂运来一堆煤，计划每天烧煤50千克，6.5天烧完，实际10天才烧完．实际每天比计划少烧煤多少千克？
<gadget id="calculator">6.5 / 10</gadget>
<output>0.65</output>

<gadget id="calculator">50 * 0.65</gadget>
<output>32.5</output>

<gadget id="calculator">50 - 32.5</gadget>
<output>17.5</output>

<result>17.5</result>