The sixth grade students participated in the "Welcome to the Asian Games" tree planting activity. Among them, the first class planted 80 trees, the second class planted more trees than the first class (9/8), the third class planted 7 more trees than the second class (7/9), and the third class planted how many trees.
六年级学生参加"迎亚运"植树活动．其中，一班植树80棵，二班植树的棵数是一班的(9/8)，三班植树的棵数比二班的(7/9)还多7棵，三班植树多少棵．
<gadget id="calculator">9 / 8</gadget>
<output>9/8 = around 1.125</output>

<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">80 * (9/8) * (7/9)</gadget>
<output>70</output>

<gadget id="calculator">70 + 7</gadget>
<output>77</output>

<result>77</result>