A philatelist bought a total of 34 stamps of 2 yuan and 5 yuan, and spent exactly 98 yuan. How many 5 yuan stamps are there?
一个集邮爱好者买了2元和5元的邮票共34张，正好用了98元．5元的邮票多少张．
<gadget id="calculator">2 * 34</gadget>
<output>68</output>

<gadget id="calculator">98 - 68</gadget>
<output>30</output>

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<result>10</result>