En un sistema de numeración de base 9, cuál es el mayor número de tres cifras diferentes

We have enough material to build a fence around a station that has a perimeter of 180 feet the width of the rectangular space must be 3 1/4 feet what must the length be

How do you solve a question like this?

Solve the equation for x.3(6x - 1) = 12 i've tried doing the math and i can't find out what i'm doing wrong