Question 1135842
a1+a2+a3=21
note, a2 is n more than a1 and a3 is n more than a2 so the sum is 3a2=21 and a2=7

a1*a3=a2+6
so a1*a3=13

a2-a1=a3-a2

a1=1
a2=7
a3=13