Posted by Zephine on Thursday, November 17, 2011 at 8:17pm.
if their ages are a,b,c,d, then
a+b+c+d = 3n + 3n+3 + 3n+6 + 3n+9 = 12n + 18
(a-5)+(b-5)+(c-5)+(d-5) = 46
a+b+c+d = 66
so, 12n+18 = 66
n=4
so, the ages are 12,15,18,21
5 years ago, they were 7,10,13,16 and added up to 46