Express the perimeter of each rectangle as single rational e

Express the perimeter of each rectangle as single rational expression. x/x + 3 x/x + 4

Perimeter of rectangle is given by:

P = 2*(L + W)

P = 2*(x/(x + 3) + x/(x + 4))

P = 2*(x*(x + 4) + x*(x + 3))/[(x + 3)*(x + 4)]

P = 2*(x^2 + 4x + x^2 + 3x)/(x^2 + 3x + 4x + 12)

P = (4x^2 + 14x)/(x^2 + 7x + 12)