Huafu School plans to repaint the 15 classrooms of the sixth grade. Each classroom is 12 meters long, 8 meters wide and 3.5 meters high. How many square meters are there to be painted on the roof and four walls of the classroom (28 square meters of doors, windows and blackboards need to be removed for each classroom)?
华附学校计划将六年级的15间教室粉刷一遍．每间教室长12米，宽8米，高3.5米．要粉刷教室的屋顶和四面墙壁(每间教室要除去门窗和黑板面28平方米)要粉刷的部分共有多少平方米？
<gadget id="calculator">70 - 28</gadget>
<output>42</output>

<gadget id="calculator">96 + 42</gadget>
<output>138</output>

<result>138</result>