There is a house with a length of 8 meters, a width of 50 decimeters, and a height of 3 meters. The top surface and surrounding walls of the house need to be painted. The area excluding the doors and windows is 2.5 square meters. How many square meters is the area to be painted?
有一房间房子，长8米，宽50分米，高3米，要粉刷房子的顶面和四周墙壁，除去门窗的面积2.5平方米，要粉刷的面积是多少平方米？
<gadget id="calculator">50 / 10</gadget>
<output>5</output>

<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<gadget id="calculator">5 * 3 * 2</gadget>
<output>30</output>

<gadget id="calculator">8 * 3 * 2</gadget>
<output>48</output>

<gadget id="calculator">48 - 2.5</gadget>
<output>45.5</output>

<gadget id="calculator">40 + 30 + 45.5</gadget>
<output>115.5</output>

<result>115.5</result>