lets assume length of 2nd piece is x
length of 1 st piece = 2x
length of 3rd piece = 3x - 11
so
x + 2x + 3x-11 = 25
6x -11=25
6x = 25+11= 36
x = 36/6 = 6
so length of 1st peice = 2x = 2×6 = 12
length of 3rd piece = 3x - 11 = 3×6-11
=18-11 = 7
so pieces are 12, 6, 7 inches