Răspuns :
a+b=140
a=2b/5
2b/5+b=140 aducem la acelasi numitor
2b+5b=700
7b=700
b=100
a+b=140
a=2/5*b
a=2b/5
2b=5a
a+b=140/*2
2a+2b= 280
2a+5a=280
7a=280/:7
a=40
b=100
a=2/5*b
a=2b/5
2b=5a
a+b=140/*2
2a+2b= 280
2a+5a=280
7a=280/:7
a=40
b=100