Answer :
x - 1st number
y - 2nd number
z - 3rd number
[tex]x=3y\\ y=2z\\ \frac{x+y+z}{3}=18\\\\ x=3y\\ z=\frac{y}{2}\\ x+y+z=54\\\\ 3y+y+\frac{y}{2}=54\\ 6y+2y+y=108\\ 9y=108\\ y=12\\\\ z=\frac{12}{2}\\ z=6\\\\ x=3\cdot12\\ x=36\\\\ \boxed{36,12,6}[/tex]
y - 2nd number
z - 3rd number
[tex]x=3y\\ y=2z\\ \frac{x+y+z}{3}=18\\\\ x=3y\\ z=\frac{y}{2}\\ x+y+z=54\\\\ 3y+y+\frac{y}{2}=54\\ 6y+2y+y=108\\ 9y=108\\ y=12\\\\ z=\frac{12}{2}\\ z=6\\\\ x=3\cdot12\\ x=36\\\\ \boxed{36,12,6}[/tex]
