A bottle of yogurt is 3.8 yuan, which is 0.3 yuan more expensive than a bottle of black tea. If you buy both bottles, how much is the total cost?
一瓶酸奶3.8元，比一瓶红茶贵0.3元，如果两瓶都要买，一共需要多少元．
<gadget id="calculator">3.8 - 0.3</gadget>
<output>3.5</output>

<gadget id="calculator">3.8 + 3.5</gadget>
<output>7.3</output>

<result>7.3</result>