Perimetro de rectangulo = 2 ancho + 2 largo
perimetro = 540 m
largo = 2ancho + 30m
ancho = x
entonces
perimetro = 2ancho + 2 largo
540m = 2.x + 2.(2x + 30m) resulevo
540m = 2x + 4x + 60m despejo
540m - 60m = 6x
480m = 6x
480m/6 = x
80 m = x
entonces
ancho = 80m largo = 2(80m) + 30m → largo = 190m
espero que te sirva, salu2!!!