Lili's mother went to the mall and bought 3 boxes of toothpaste and 2 bags of washing powder. The total cost was 30.8 yuan. A bag of washing powder was 6.7 yuan. How much is a box of toothpaste?
丽丽的妈妈去商场买了3盒牙膏和2袋洗衣粉，一共花了30.8元，一袋洗衣粉6.7元，一盒牙膏多少钱？
<gadget id="calculator">6.7 * 2</gadget>
<output>13.4</output>

<gadget id="calculator">30.8 - 13.4</gadget>
<output>17.4</output>

<gadget id="calculator">17.4 / 3</gadget>
<output>5.8</output>

<result>5.8</result>