Les trois nombres sont: a, b, c. Nous savons que:
a + b +c = 1229
b = 2a
c -b = 14
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c - b = 14 -> c = 14 + 2a
a + b +c = a + 2a + 14 + 2a -> 5a + 14 = 1229; 5a = 1229 - 14 = 1215
a = 1215 /5 -> a = 243
b = 2a = 2 x 243 -> b = 486
c = 14 + 2a = 14 + 2 x 243 -> c = 500
a + b +c = 1229
243 + 486 + 500 = 1229
1229 = 1229 (C'est vraiment!)