6)
x, y, z direct proportionale cu 8, 12, 18⇔[tex] \frac{x}{8}= \frac{y}{12}= \frac{z}{18} [/tex]
x+y+z=76
x/8=y/12⇒12x=8y⇒x=8y/12⇒x=2y/3
y/12=z/18⇒12z=18y⇒z=18y/12⇒z=3y/2
x+y+z=76⇒2y/3+y+3y/2=76⇒(4y+9y+6y)/6=76⇒19y/6=76⇒y=76·6/19⇒y=24
x=2·24/3⇒x=2·8⇒x=16
z=3·24/2⇒z=3·12⇒z=36
x=16
y=24
z=36
7)
