Răspuns :
a+b=423
a+a+7=423
2a+7=423
2a=423-7
2a=416
a=416:2
a=208
b=208+7
b=215
V:208+215=423
a+a+7=423
2a+7=423
2a=423-7
2a=416
a=416:2
a=208
b=208+7
b=215
V:208+215=423
a+b=423
a=b+7
b+7+b=423⇒2b+7=423⇒2b=423-7⇒2b=416⇒b=416÷2⇒b=208
a=208+7⇒a=215
verificare
215+208=423
a=b+7
b+7+b=423⇒2b+7=423⇒2b=423-7⇒2b=416⇒b=416÷2⇒b=208
a=208+7⇒a=215
verificare
215+208=423