Let the numbers be a−d,a,a+d ∴a+d+a+a−d=21 ⇒‌‌3a=21 ⇒‌‌a=7 Again, (a−d)(a+d)=45 ⇒‌‌a2−d2=45 ⇒‌‌(7)2−d2=45 ⇒‌‌49−d2=45 ⇒‌‌d2=4 ⇒‌‌d=±2 ∴ Numbers are 5,7,9 or 9,7,5 ∴ Products of three numbers =5×7×9 =315