A trapezoidal orchard has an upper base of 50 meters, a lower base of 70 meters, and a height of 80 meters. If each fruit tree covers an area of 15 square meters, how many fruit trees can be planted in this orchard?
一块梯形果园，上底是50米，下底是70米，高是80米，如果每棵果树占地15平方米，这个果园可以种多少棵果树？
<gadget id="calculator">50 + 70</gadget>
<output>120</output>

<gadget id="calculator">80 / 2 / 15</gadget>
<output>8/3 = around 2.666667</output>

<gadget id="calculator">120 * (8/3)</gadget>
<output>320</output>

<result>320</result>