The school distributes the planting task of a batch of saplings to the fourth, fifth and sixth grades according to 2:3:4. It is known that the fourth and fifth grades are divided into 80 trees, how many are the sixth grades?
学校将一批树苗的栽种任务按2：3：4分给四、五、六三个年级，已知四年级和五年级共分到80棵，六年级分得多少棵？
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">2 + 3 + 4</gadget>
<output>9</output>

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

<gadget id="calculator">80 / (5/9)</gadget>
<output>144</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">144 * (4/9)</gadget>
<output>64</output>

<result>64</result>