Students in the fourth, fifth and sixth grades of Yuying Primary School have to plant 450 trees in total. It is known that the fourth grade has completed their tasks (5/6), the fifth grade has completed their tasks (2/3), and the sixth grade has already planted (5/9) have finished their tasks, and they have planted the same number of trees. Ask: How many trees are left that have not been planted?
育英小学四、五、六年级学生共要栽树450棵，已知四年级已经栽完了自己任务的(5/6)，五年级已经栽完了自己任务的(2/3)，六年级已经栽完了自己的任务的(5/9)，并且它们已经栽完的棵数同样多，问：一共还剩下多少棵树没有栽？
<gadget id="calculator">4 + 5 + 6</gadget>
<output>15</output>

<gadget id="calculator">450 / 15</gadget>
<output>30</output>

<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">1 / (5/6)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1 / (6/5)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">30 * 4 * (5/6) * 3</gadget>
<output>300</output>

<gadget id="calculator">450 - 300</gadget>
<output>150</output>

<result>150</result>