The school went to plant trees. A total of 850 leaves were planted in the fourth, fifth and sixth grades, of which 150 were planted in the fourth grade. The ratio of the number of trees planted in the fifth and sixth grades was 5:9. How many trees were planted in the sixth grade?
学校去植树，四五六年级共植树叶850棵，其中四年级植了150棵，五、六年级植树的棵数比是5：9，六年级植树多少棵？
<gadget id="calculator">850 - 150</gadget>
<output>700</output>

<gadget id="calculator">5 + 9</gadget>
<output>14</output>

<gadget id="calculator">9 / 14</gadget>
<output>9/14 = around 0.642857</output>

<gadget id="calculator">700 * (9/14)</gadget>
<output>450</output>

<result>450</result>