A+B+C=418
A=2C
B=A/4-2 adica B=2C/4-2 numitor comun 4
B=(2C-2x4)/4
B=2(C-4)/4 simplificam cu 2
B=(C-4)/2
inlocuim in prima relatie
2C+(C-4)/2+C=418
numitor comun 2
(2cx2+C-4+2C)/2=836/2
inmultim totul cu 2 ,sa scapam de numitor
4C+C-4+2C=836
7C=836+4
7C=840
C=840:7
C=120 timbre
B=(120-4):2
B=116:2
B=58 timbre
A=2x120
A=240 timbre
verificare
240+58+120=418 timbre