Respuesta :
P = 2l+2w
substitute P and w
72 = 2l + 2(19)
72 = 2l + 38
subtract 38 from each side
72-38 = 2l + 38-38
34 = 2l
divide by 2
34/2 = 2l/2
17 = l
L = 17 inches
[tex]P=2l+2w\\\\\text{We have}\ P=72\ in\ \text{and}\ w=19\ in.\\\\\text{Substitute:}\\\\2l+2(19)=72\\\\2l+38=72\qquad\text{subtract 38 from both sides}\\\\2l=34\qquad\text{divide both sides by 2}\\\\\boxed{l=17}\\\\Answer:\ \boxed{17\ in}[/tex]