There are 120 boys and 80 girls participating in a mathematics competition in a certain school. There are 120 girls and 80 boys participating in the language competition. It is known that a total of 260 students in the school participated in the competition, and 75 boys participated in both subjects. Then how many girls only participated in the mathematics competition but did not participate in the Chinese competition.
某校参加数学竞赛有120名男生，80名女生．参加语文竞赛有120名女生，80名男生．已知该校总共有260名学生参加了竞赛，其中有75名男生两科竞赛都参加了，那么只参加数学竞赛而没有参加语文竞赛的女生人数是多少人．
<gadget id="calculator">80 - 75</gadget>
<output>5</output>

<gadget id="calculator">120 + 5</gadget>
<output>125</output>

<gadget id="calculator">260 - 125</gadget>
<output>135</output>

<gadget id="calculator">80 - 135</gadget>
<output>-55</output>

<gadget id="calculator">120 + (-55)</gadget>
<output>65</output>

<gadget id="calculator">80 - 65</gadget>
<output>15</output>

<result>15</result>