Dongdong has 7 notebooks. After Qiangqiang gave Dongdong 2, the number of Qiangqiang's notebooks is exactly three times that of Dongdong. How many notebooks did Qiangqiang originally have.
东东有7个本子，强强送给东东2个后，强强的本子数刚好是东东的3倍，强强原来有多少个本子．
<gadget id="calculator">7 + 2</gadget>
<output>9</output>

<gadget id="calculator">9 * 3</gadget>
<output>27</output>

<gadget id="calculator">27 + 2</gadget>
<output>29</output>

<result>29</result>