Răspuns :
7a+3b=29
4a+3a+3b=29
4a+3(a+b)=29
4a+3*7=29
4a=29-21
4a=8
a=8:4
a=2 b=7-a=7-2=5
4a+3a+3b=29
4a+3(a+b)=29
4a+3*7=29
4a=29-21
4a=8
a=8:4
a=2 b=7-a=7-2=5