Răspuns :
a+b=24
a-b=12
_________
a=12+b
==>
12+b+b=24
12+2b=24
2b=24-12
2b=12
b=12:2
b=6
a+b=24
a+6=24
a=24-6
a=18
VERIFICARE:
a+b=24
18+6=24 adevărat
a-b=12
18-6=12 adevărat
a+b=24
a-b=12
_________
a=12+b
==>
12+b+b=24
12+2b=24
2b=24-12
2b=12
b=12:2
b=6
a+b=24
a+6=24
a=24-6
a=18
VERIFICARE:
a+b=24
18+6=24 adevărat
a-b=12
18-6=12 adevărat