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n + n + 1 + n + 2 = 129
3 n = 129 - 3
3 n = 126
n = 42
42 + 43 + 44 = 129
cahier = x
classeur = 1.5 x
7 x + 5 ( 1.5 x ) + 11.25 = 44 .60
7 x + 7.5 x = 44.60 - 11.25
14 .5 x = 33.35
x = 2.3
cahier = 2.30
classeur = 2.3 x 1.5 = 3.45