Respuesta :

x + (x+3) = 28 
2 x + 3 = 28 
2x = 25 
x = 12.5 
x+3 = 15.5 

28-15.5= 12.5

The two lengths are 15.5 and 12.5. 
Let one piece = x.ft
Let other piece = 3ft longer i.e xft + 3ft 
I am leaving this answer for others beginners to consider