The sum of A, B and C is 10.43, and the sum of A and B is 6.18. The sum of A and C is 6.75, what is A's number?
甲、乙、丙三数的和是10.43，甲、乙两数的和是6.18．甲、丙两数的和是6.75，甲数是多少．
<gadget id="calculator">10.43 - 6.75</gadget>
<output>3.68</output>

<gadget id="calculator">6.18 - 3.68</gadget>
<output>2.5</output>

<result>2.5</result>