The total output of rapeseed in Dashu Village this year is 98.9 tons, an increase of 12.9 tons compared with last year. How much is the increase?
大树村今年油菜籽的总产量是98.9吨，比去年增产12.9吨，增产百分之几？
<gadget id="calculator">98.9 - 12.9</gadget>
<output>86</output>

<gadget id="calculator">12.9 / 86</gadget>
<output>0.15</output>

<result>0.15</result>