Three numbers in A.P.: (a-d,\ a,\ a+d)

Sum: (3a=24\implies a=8)

Product: (8(64-d^2)=440\implies64-d^2=55\implies d^2=9\implies d=\pm3)

Numbers: (5,8,11) or (11,8,5)

Answer: (5,8,11)