Three students came to the bake sale to shop. The sum of their ages is 33. The product of their ages is 1320. How old are they?

let the ages of three persons be a-d,a,a+d

then,
a-d+a+a+d=33
=>3a=33=>a=11
and,a(a-d)(a+d)=1320
=>11(121-d^2)=1320
=>d^2=1
=>d=1
therefore,the ages of the three persons are
11,10,12