x:9=C₁ rest 5⇒x=9C₁+5⇒x-5=9C₁
x:12=C₂ rest 5⇒x=12C₂+5⇒x-5=12C₂
x:15=C₃ rest 5⇒x=15C₃+5⇒x-5=15C₃
Calculam c.m.m.m.c. al nr.9,12,15
9=3²
12=2²x3
15=3x5
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[9,12,15]=2²x3²x5=4x9x5=36x5=180
x-5=180⇒x=180+5⇒x=185
185:9=20 rest 5
185:12=15 rest 5
185:15=12 rest 5