Răspuns :
A-b=12
2a+3b=89
A=b+12
2×(b+12)+3b=89
2b+24+3b=89
5b=89-24
5b=65|:5
B=13
A=13+12
A=25
1=a
2=b
a-b=12
ax2+bx3=89
2a+3b=89
a=3b
3b-b=12
2b=12
b=6
a=3x6
a=18
18-6=12
2=b
a-b=12
ax2+bx3=89
2a+3b=89
a=3b
3b-b=12
2b=12
b=6
a=3x6
a=18
18-6=12