The students planted trees. The fifth grade planted the sixth grade (4/5) and the fourth grade (8/7). It is known that there are 200 trees planted in the sixth grade and how many trees are planted in the fourth grade.
同学们去植树，五年级植的树是六年级的(4/5)，是四年级植的(8/7)，已知六年级植树200棵，四年级植树多少棵．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">8 / 7</gadget>
<output>8/7 = around 1.142857</output>

<gadget id="calculator">(4/5) / (8/7)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">200 * (7/10)</gadget>
<output>140</output>

<result>140</result>