There is a trapezoidal orchard, the bottom is 80 meters, 20 meters longer than the top, and 50 meters high. On average, one fruit tree is planted every 7 square meters. How many fruit trees can be planted in this land?
有一块梯形果园，下底80米，比上底长20米，高50米，平均每7平方米栽一棵果树，这块地共可栽多少棵果树？
<gadget id="calculator">80 - 20</gadget>
<output>60</output>

<gadget id="calculator">60 + 80</gadget>
<output>140</output>

<gadget id="calculator">50 / 2 / 7</gadget>
<output>25/7 = around 3.571429</output>

<gadget id="calculator">140 * (25/7)</gadget>
<output>500</output>

<result>500</result>