The shape of an apple orchard is trapezoid, the upper base is 80m, the lower base is 90m, and the height is 100m. If each apple covers an area of 10m**2, how many apple trees are there in this orchard?
一个苹果园的形状是梯形，上底是80m，下底是90m，高是100m．如果每棵苹果占地10m**2，这个果园共有苹果树多少棵？
<gadget id="calculator">80 + 90</gadget>
<output>170</output>

<gadget id="calculator">100 / 2 / 10</gadget>
<output>5</output>

<gadget id="calculator">170 * 5</gadget>
<output>850</output>

<result>850</result>