trapezoidal orchard has a lower base of 240m, an upper base of 180m, and a height of 60m. If each fruit tree covers an area of 9 square meters, how many fruit trees are there in this orchard?
一个梯形果园，它的下底是240m，上底是180m，高是60m．如果每棵果树占地9平方米，这个果园共有果树多少棵？
<gadget id="calculator">240 + 180</gadget>
<output>420</output>

<gadget id="calculator">60 / 2 / 9</gadget>
<output>10/3 = around 3.333333</output>

<gadget id="calculator">420 * (10/3)</gadget>
<output>1_400</output>

<result>1_400</result>