Let x be the length of the 1st side so that 3x is the length of the 2nd side and \(\displaystyle{3}{x}−{63}{x}−{6}\) is the length of the 3rd side. The perimeter is 239 cm so we can write:

\(\displaystyle{x}+{3}{x}+{\left({3}{x}−{6}\right)}={239}\)

Solve for x:

\(\displaystyle{7}{x}−{6}={239}\)

\(\displaystyle{x}={35}\)

So, the 1st side measures 35 cm, the 2nd side measures \(\displaystyle{3}{\left({35}\right)}={105}{c}{m},\) and the 3rd side measures \(\displaystyle{3}{\left({35}\right)}-{6}={99}{c}{m}.\)

\(\displaystyle{x}+{3}{x}+{\left({3}{x}−{6}\right)}={239}\)

Solve for x:

\(\displaystyle{7}{x}−{6}={239}\)

\(\displaystyle{x}={35}\)

So, the 1st side measures 35 cm, the 2nd side measures \(\displaystyle{3}{\left({35}\right)}={105}{c}{m},\) and the 3rd side measures \(\displaystyle{3}{\left({35}\right)}-{6}={99}{c}{m}.\)