Xiaoqing said: "I bought 8 kinds of stationery." Xiaolin said: "I bought 7 kinds of stationery." Among them were pens, erasers, scissors and exercise books. They both bought them. May I ask how many kinds they bought in total? Stationery?
小青说："我买了8种文具．"小林说："我买了7种文具．"其中有钢笔、橡皮、剪刀和练习本，她们俩都买了，请问她俩一共买了多少种文具？
<gadget id="calculator">7 - 4</gadget>
<output>3</output>

<gadget id="calculator">8 + 3</gadget>
<output>11</output>

<result>11</result>