Class 6 of Hongxing Elementary School participated in tree planting. Class 1 planted 90 trees. Class 2 planted trees from Class 1 (4/3) and Class 3 (6/7). How many trees are planted in the third class?
红星小学六年级三个班同学参加植树，一班植了90棵，二班植的棵树是一班的(4/3)，同时又是三班的(6/7)．三班植树多少棵？
<gadget id="calculator">4 / 3</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">(4/3) / (6/7)</gadget>
<output>14/9 = around 1.555556</output>

<gadget id="calculator">90 * (14/9)</gadget>
<output>140</output>

<result>140</result>