A triangle and a parallelogram have the same base and height. The sum of their areas is 15. What is the area of the parallelogram in square centimeters?
一个三角形与一个平行四边形等底等高，它们的面积之和是15，平行四边形面积是多少平方厘米．
<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">15 * (2/3)</gadget>
<output>10</output>

<result>10</result>