First set up the equation based on the description.
[tex] \frac{1}{3} [/tex] x + 16 = 3x
Use subtraction to get the "x"s on one side of the equation. You can next subtract [tex] \frac{1}{3} [/tex] x from both sides.
16 = [tex] \frac{8}{3} [/tex] x
Now you can multiply both sides of the equation by [tex] \frac{3}{8} [/tex] to solve for x
x = 6