There are 49 students in a certain class, among which male students (2/5) and female students (3/8) participate in the mathematics group, how many students in this class do not participate in the mathematics group?
某班有49名同学，其中男同学的(2/5)和女同学的(3/8)参加了数学小组，那么这个班中没有参加数学小组的同学有多少名．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">25 * (2/5)</gadget>
<output>10</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">24 * (3/8)</gadget>
<output>9</output>

<gadget id="calculator">10 + 9</gadget>
<output>19</output>

<gadget id="calculator">49 - 19</gadget>
<output>30</output>

<result>30</result>