Xinhua Primary School planted 230 trees this year, 15% more than last year. How many trees were planted last year?
新华小学今年植树230棵，比去年多植了15%，去年植树多少棵？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 + (3/20)</gadget>
<output>23/20 = around 1.15</output>

<gadget id="calculator">230 / (23/20)</gadget>
<output>200</output>

<result>200</result>