cotton field harvested 30 tons of cotton last year, an increase of 5 tons over the previous year. By what percentage did the cotton field increase?
一块棉花地去年收棉花30吨，比前年增产了5吨，这块棉花地增产了百分之几？
<gadget id="calculator">30 - 5</gadget>
<output>25</output>

<gadget id="calculator">5 / 25</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>