a+b+c+d+e+f=439
a+6=f⇒a=f-6
b-6=f⇒b=f+6
c:6=f⇒c=6f
dx6=f⇒d=f:6
e-2x6=f
e-12=f⇒e=f+12
Inlocuim
f-6+f+6+6f+f:6+f+12+f=439
10f+f:6+12=439
10f+f:6=439-12
10f+f:6=427
60f+f=427x6
61f=2562
f=2562:61
f=42
a=f-6⇒a=42-6⇒a=36
b=f+6⇒b=42+6⇒b=48
c=6f⇒c=6x42⇒c=252
d=f:6⇒d=42:6⇒d=7
e=f+12⇒e=42+12⇒e=54
Deci nr.sunt:
a=36
b=48
c=252
d=7
e=54
f=42
a+b+c+d+e+f=439
36+48+252+7+54+42=439