a+b+c=3600
a:b=1 rest c⇒a=b+c
b= 300+c
a+b+c=3600 si a=b+c inlocuim
b+c+b+c=3600
2b+2c=3600
2 (b+c)=3600
b+c=3600:2
b+c=1800
dar b=300+c
deci 300+c+c=1800
300+2c=1800
2c=1800-300
2c=1500
c=1500:2
c=750
acum avem c=750 si b=300+c⇒c=300+750⇒c=1050
acum avem b=1050 si c=750 iar a=b+c⇒a=1050+750⇒a=1800