Use 90 cm long iron wire to form a right triangle. The ratio of the lengths of the three sides of this triangle is 2:3:4. What is the area of this right triangle in square centimetres.
用90厘米长的铁丝围成一个直角三角形，这个三角形三条边长度的比是2：3：4．这个直角三角形的面积是多少平方厘米．
<gadget id="calculator">2 + 3 + 4</gadget>
<output>9</output>

<gadget id="calculator">90 / 9</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">20 * 15</gadget>
<output>300</output>

<result>300</result>