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2014-08-02T15:04:41+03:00
A+2b=25

a=25-2b

2a+b=20

2(25-2b)+b=20

50-4b+b=20

-3b=20-50

-3b= -30

3b=30

b=10

a=25-2*10= 25-20=5
Aa
Ok ms
2a+b=20 <=> 2a+(25-a)/2= 20 aduci la acelasi numitor
4a+25-a=40 <=>3a=40-25 <=>3a=15 =>a=5
b=(25-5)/2=20/2=10