A parallelogram is a plank with a base of 5 meters and a height of 3 meters. Calculated at 28 yuan per square meter, what is its price?
一块平行四边形的木板，底为5米，高为3米．以每平方米28元计价，它的价格是多少？
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">28 * 15</gadget>
<output>420</output>

<result>420</result>