A cuboid is 30 cm long and has a square cross section. If the length increases by 5 cm, the surface area increases by 80 cm2. What is the surface area of the original cuboid?
一个长方体长30cm，横截面是正方形，如果长增加5cm，表面积就增加80平方厘米，那么原来这个长方体的表面积是多少平方厘米？
<gadget id="calculator">80 / 5</gadget>
<output>16</output>

<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<gadget id="calculator">4 * 4 * 2</gadget>
<output>32</output>

<gadget id="calculator">4 * 30 * 4</gadget>
<output>480</output>

<gadget id="calculator">32 + 480</gadget>
<output>512</output>

<result>512</result>