Three people, A, B, and C, have done 183 math problems in total. The number of problems that B has solved is 4 times less than that of C, and the number of problems that A has solved is 7 times more than that of C. How many problems has C done? what is the correct formula
甲乙丙三人共做了183道数学题，乙做的题比丙的2倍少4道，甲做的题比丙的3倍多7道，丙做了多少题？正确算式是多少
<gadget id="calculator">4 - 7</gadget>
<output>-3</output>

<gadget id="calculator">183 + (-3)</gadget>
<output>180</output>

<gadget id="calculator">1 + 2 + 3</gadget>
<output>6</output>

<gadget id="calculator">180 / 6</gadget>
<output>30</output>

<result>30</result>