The two sides of a triangle are 3 decimeters and 4 decimeters respectively, and the third side must be shorter than how many decimeters.
一个三角形的两条边长分别是3分米、4分米，第三条边一定比多少分米短．
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<result>7</result>