There are several students in a certain school participating in the composition and mathematics competitions. Among them, the number of students participating in the mathematics competition accounts for (2/3) of the total number of all competitions, and the number of students participating in the composition competition accounts for (3/4) of the total number of all competitions. There are 45 people who participated in both, how many people participated in the mathematics competition but not in the composition competition?
某学校有若干名学生参加作文和数学两科竞赛，其中参加数学竞赛的人数占全部竞赛总人数的(2/3)，参加作文竞赛的占全部竞赛总人数的(3/4)，两科都参加的有45人，参加数学竞赛而未参加作文竞赛的有多少人？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/3) - (1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">45 / (5/12)</gadget>
<output>108</output>

<gadget id="calculator">108 * (1/4)</gadget>
<output>27</output>

<result>27</result>