Răspuns :
a+b=80
b=a+2
a+a+2=80
2a+2=80
2a=80-2
2a=78
a=78÷2
a=39
b=39+2
b=41
b=a+2
a+a+2=80
2a+2=80
2a=80-2
2a=78
a=78÷2
a=39
b=39+2
b=41
a+b=80
b=a+2
a+a+2=80
2×a+2=80
2×a=80-2
2×a=78
a=78÷2
a=39
b=a+2
b=39+2
b=41
b=a+2
a+a+2=80
2×a+2=80
2×a=80-2
2×a=78
a=78÷2
a=39
b=a+2
b=39+2
b=41