Friday

October 9, 2015
Posted by **Zephine** on Thursday, November 17, 2011 at 8:17pm.

- algebra -
**Steve**, Friday, November 18, 2011 at 12:23pmif 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