A triangle and a parallelogram have the same base and the same height, and the sum of their areas is 18 square centimeters. What is the area of the parallelogram in square centimeters?
一个三角形和一个平行四边形的底相等高相等，它们的面积和是18平方厘米，平行四边形的面积是多少平方厘米．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 + (1/2)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">18 / (3/2)</gadget>
<output>12</output>

<result>12</result>