There are three questions A, B, and C in the arithmetic test. If you can't answer question B, you can't answer question C either. In a class of 50 students, there are 32 people who can solve problem A, 48 people who can solve problem B, and none of them can't even solve a problem. Among the number of people who can do both A and B, 60% of them can also do C, which is equivalent to 72% of those who can do C. So how many people can make C but not A.
算术测验出了A、B、C三道题．如果B题答不上时，C题也答不上．在50人的班级里，能做出A题的有32人，能做出B题的有48人，没有连一道题也做不上的．在既能做A题也能做出B题的人数中，有60%的人又能做出C题，这些人相当于会做出C题的72%．那么能做出C，而不能做出A题的有多少人．
<gadget id="calculator">32 - 50</gadget>
<output>-18</output>

<gadget id="calculator">48 + (-18)</gadget>
<output>30</output>

<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 * (3/5)</gadget>
<output>18</output>

<gadget id="calculator">72 / 100</gadget>
<output>18/25 = around 0.72</output>

<gadget id="calculator">18 / (18/25)</gadget>
<output>25</output>

<gadget id="calculator">25 - 18</gadget>
<output>7</output>

<result>7</result>