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Se stie ca ; a:b=3. b:2=c. a-b=40. Afla: 3a-4b+5c

Răspuns :

b=2c
a=3b=6c
a-b=40
6c-2c=40
c=40:4=10
b=10x2=20
a=20x3=60
3a-4b+5c
3x60-4x20+5x10=
180-80+50=150