There are 18 girls in Class 2, Grade 1 of Chengdu Foreign Language School, 12 of whom live in Chengdu, and the remaining 6 are from outside the city. The number of boys is less than that of girls, but more than girls (7/9), and the number of boys from inside and outside the city is equal. This year, the whole class participated in the voluntary tree planting. Girls planted an average of 4 trees, and boys planted an average of 5 trees. How many trees were planted in the class?
成都外国语学校初一年级二班有女生18人，其中12人家住成都市，其余6人来自市外．男生的人数比女生少，但比女生的(7/9)多，来自市内、外男生人数相等．今年全班同学参加义务植树，女生平均每人种4棵，男生平均每人种5棵，全班共植树多少棵？
<gadget id="calculator">18 * 4</gadget>
<output>72</output>

<gadget id="calculator">16 * 5</gadget>
<output>80</output>

<gadget id="calculator">72 + 80</gadget>
<output>152</output>

<result>152</result>