To buy a cup, mother pays 2 yuan for one piece, 1 yuan for 1 piece, and 20 cents for 2 pieces. What is the price of this cup?
买一个杯子，妈妈付出1张2元，1张1元，2张2角，这个杯子的价格是多少元．
<gadget id="calculator">2 + 1 + 0.4</gadget>
<output>3.4</output>

<result>3.4</result>