There are 42 students in a class, and 30 of them participate in the long-distance running competition. There are 20 girls in this class, and 5 of the boys did not participate in the long-distance running competition, so how many of the girls did not participate in the long-distance running competition?
一个班有42名同学，其中有30人参加长跑比赛．这个班女生有20人，男生中有5人没有参加长跑比赛，那么女生中有多少人没有参加长跑比赛？
<gadget id="calculator">42 - 20</gadget>
<output>22</output>

<gadget id="calculator">22 - 5</gadget>
<output>17</output>

<gadget id="calculator">30 - 17</gadget>
<output>13</output>

<gadget id="calculator">20 - 13</gadget>
<output>7</output>

<result>7</result>