In the "Welcome to the Olympics" tree planting activity, I hope that the sixth graders will plant 84 trees, and the number of trees planted by the fifth graders will be the number of sixth graders (6/7). How many trees are planted in fifth grade?
在"迎奥运"植树活动中，希望小学六年级同学植树84棵，五年级植树的棵数是六年级的(6/7)．五年级植树多少棵？
<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">84 * (6/7)</gadget>
<output>72</output>

<result>72</result>