The school assigned the task of planting 560 trees to each class according to the number of students in the three classes of the sixth grade. The first class has 47 people, the second class has 45 people, and the third class has 48 people. How many trees should the second class plant?
学校把560棵数的种植任务，按照六年级三个班的人数分配给各班．一班有47人，二班有45人，三班有48人．二班应种树多少棵棵．
<gadget id="calculator">47 + 45 + 48</gadget>
<output>140</output>

<gadget id="calculator">45 / 140</gadget>
<output>9/28 = around 0.321429</output>

<gadget id="calculator">560 * (9/28)</gadget>
<output>180</output>

<result>180</result>