The sum of the upper and lower bases of an isosceles trapezoid is 25 decimeters, and the length of one waist is 9 decimeters. What is the circumference?
一个等腰梯形上、下底之和是25分米，一条腰长9分米，周长是多少．
<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<gadget id="calculator">25 + 18</gadget>
<output>43</output>

<result>43</result>