Math problem in the fourth grade of primary school: the sum of A and B is 18, the sum of B and C is 20, and the sum of A and C is 24. What are the three numbers A, B and C respectively?
A+B = 18 B+C =20 A+C =24, and we get: 2 A +2 B +2 C = 18=20+24=62, so A+B+C =3 1 because a+b = So c = 31-18 =13b = 20-c = 20-13 = 7. a = 18-B = 18-7 = 16544。
So a =11; b = 7； C = 13。
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