b+c+f=5300
b=c+1970
b=f-205
Egalam cele doua expresii in functie de b.
c+1970=f-205
1970+205=f-c
2175=f-c =>f=c+2175
Rescriem expresia initiala astfel incat sa aiba o singura necunoscuta :
c+1970+c+c+2175=5300
3c=5300-4145
3c=1155 =>c=385
f=385+2175 =>f=2560
b=385+1970 =>b=2355