Question

a+b=30 ; b este de 2 ori mai mare decat a ;

Answer 1

A /----/---/;b/----/;3 segmente;30:3=10 b;10×2=20 a

Answer 2

$a+b = 30 \\ b=2a \\ a+2a= 30 \\ 3a=30 \\ a=10 \\ b=20$