It is given in the question that,
A triangle with a perimeter of 66 inches has one side that is 16 inches long. the length of the other two sides have a ratio of 2:3.
Let the other two sides are of length 2x and 3x respectively .
And perimeter is the sum of the lengths of all three sides, that is

So the other two sides are

And the length of the longest side is 30 inches .