Analysis: Suppose these three numbers are A, B and C, because these three numbers are arithmetic progression, so b= 1/2(a+c).

A+B+C = 3/2 (A+C) = 2 1，-A+C = 14-B = 7。

abc=7*ac= 168 - ac=24

A+c= 14 and ac=24 give:

a( 14-a)=24

Get a= 12, c=2 or a=2, c= 12.