A, B, and C have done a total of 183 math problems, B's number of questions is 4 times less than C's, and A's number of questions is 7 times more than C's. How many questions did C do? 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．丙做了多少道题？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>