Uncle Zhang bought two old hens at the vegetable market, each weighing 4 kilograms, and the price of the chickens was 15 yuan per kilogram. Little friend, please do the math for Uncle Zhang, how much did he spend on buying chicken today?
张大伯上菜场买了两只老母鸡，每只鸡重4千克，鸡的价格是每千克15元．小朋友，请你帮张大伯算一算，他今天买鸡共用了多少钱？
<gadget id="calculator">4 + 4</gadget>
<output>8</output>

<gadget id="calculator">15 * 8</gadget>
<output>120</output>

<result>120</result>