The postal department stipulates that for each letter weighing 20g (if it is less than 20g, it will be calculated as 20g), the postage is 1.20 yuan, and the letter weighs 30g, how much is the postage?
邮政部门规定：信件每重20g(不足20g按20g计算)，需付邮资1.20元，明明信重30g，需付邮资多少元？
<gadget id="calculator">40 / 20</gadget>
<output>2</output>

<gadget id="calculator">2 * 1.2</gadget>
<output>2.4</output>

<result>2.4</result>