Răspuns :

dublu=2x
triplu=3x
x+2x+3x=24
6x=24
x=24:6
x=4

figurativ

numar |__n__|
dublu  
|__n__||__n__|
triplu   
|__n__||__n__||__n__|

deci n+(n+n)+(n+n+n)=24
6xn=24
n=24:6
n=4
I x
II 2x        }24
III 3x

x+2x+3x=24
6x=24
x=24/6
I x=4
II 2x=2*4=8
III 3x=3*4=12