An umbrella is 13.2 yuan, a bottle of ink is 9.8 yuan cheaper than it, and a pencil case is 2.9 yuan more expensive than a bottle of ink. How much is a stationery box?
一把伞13.2元，一瓶墨水比它便宜9.8元，一个文具盒比一瓶墨水贵2.9元．一个文具盒多少元？
<gadget id="calculator">13.2 - 9.8</gadget>
<output>3.4</output>

<gadget id="calculator">3.4 + 2.9</gadget>
<output>6.3</output>

<result>6.3</result>