Răspuns :
a+b=7000
a=b+9000
inlocuim necunoscutele:
b+9000+b=70000
2b=61000
b=61000:2
b=30500
a+30500=70000
a=70000-30500
a=39500
proba:
30500+39500=70000
a=b+9000
inlocuim necunoscutele:
b+9000+b=70000
2b=61000
b=61000:2
b=30500
a+30500=70000
a=70000-30500
a=39500
proba:
30500+39500=70000