The monthly water fee is 2 yuan per ton for less than 20 tons, and 3 yuan per ton for more than 20 tons. The school shared 70 tons of water last month. How much should I pay for water last month?
水费月收费标准是20吨以内的每吨2元，超过20吨的每吨3元，学校上个月共用水70吨，上个月应该缴纳水费多少元？
<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">70 - 20</gadget>
<output>50</output>

<gadget id="calculator">50 * 3</gadget>
<output>150</output>

<gadget id="calculator">40 + 150</gadget>
<output>190</output>

<result>190</result>