The school assigned the task of planting 560 trees to the fourth, fifth and sixth grades according to the ratio of 4:5:7. How many trees should be planted in each of the three grades?
学校把560棵的植树任务按4：5：7分给四、五、六三个年级完成．三个年级各应植树多少棵？
<gadget id="calculator">4 + 5 + 7</gadget>
<output>16</output>

<gadget id="calculator">560 / 16</gadget>
<output>35</output>

<gadget id="calculator">35 * 7</gadget>
<output>245</output>

<result>245</result>