rectangular iron sheet is 30 cm long and 25 cm wide. Now cut off a square with a side length of 5 cm from each of the four corners, and then make a box without a lid. How much iron sheet did you use to make the box?
一块长方形的铁皮长30厘米，宽25厘米，现在分别从四个角各切掉一个边长为5厘米的正方形，然后做成一个无盖的盒子．做盒子用了多少铁皮？
<gadget id="calculator">30 * 25</gadget>
<output>750</output>

<gadget id="calculator">5 * 5 * 4</gadget>
<output>100</output>

<gadget id="calculator">750 - 100</gadget>
<output>650</output>

<result>650</result>