The school bought 200 saplings, the teacher planted 10%, and the rest was distributed to the fifth and sixth graders at a ratio of 4:5. How many trees should the sixth grader plant?
学校买了200棵树苗，老师栽种了10%，余下的按4：5分配给五、六年级学生栽种，六年级要栽种多少棵树？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">200 * (9/10) * (5/9)</gadget>
<output>100</output>

<result>100</result>