205 m
let x be the length of one piece then the other piece is 2x + 15
The sum of the 2 pieces equals 300 m , hence
x + 2x + 15 = 300
3x + 15 = 300 ( subtract 15 from both sides )
3x = 285 ( divide both sides by 3 )
x = 95
length of longer piece = (2 × 95 ) + 15 = 190 + 15 = 205 m
