A triangle has side lengths of left parenthesis, 9, f, plus, g, right parenthesis(9f+g) centimeters, left parenthesis, 5, f, plus, 9, h, right parenthesis(5f+9h) centimeters, and left parenthesis, 2, h, plus, 7, g, right parenthesis(2h+7g) centimeters. Which expression represents the perimeter, in centimeters, of the triangle?