Question

afla nr a b c daca a +b=c;a-b=b;b+c =20

Answer 1

a+b=c
a-b=b    a=2b
b+c=20
2b+b=c
c=3b
b+3b=20
4b=20
b=5
a=2x5  a=10
c=3x5=15

Answer 2

a+b=c
a-b=b=> a=2b
2b+b=c
3b=c
c=3b
b+3b=20
4b=20=> b= 5
5+c=20
c=15
a+b=15
a+5=15
a=10
a=10 , b=5 , c=15