Fence a flower bed with a length of 15 meters and a width of 5 meters. The fence is 8 yuan per meter. How much is the total cost?
给长15米，宽5米的花坛围上篱笆，篱笆每米8元，一共需要多少元？
<gadget id="calculator">15 + 5</gadget>
<output>20</output>

<gadget id="calculator">20 * 2 * 8</gadget>
<output>320</output>

<result>320</result>