let the length of shortest side be - x
length of medium side - x +3
length of longest side - x +3 + 11
so , according to question
=> x + x +3 + x +3 + 11 = 59
=> x + x +x + 3 + 3 + 11 = 59
=> 3x = 59 - 17
=> 3 x = 42
=> x = 42/3
=> x = 14
Shortest side = x = 14
medium side = x + 3 = 14+3 = 17
longest side = x + 3 +11 = 14 + 3 + 11 = 28