Question 507143
let nancy's dog age be 'N'
let susie's dog age be 'S'

"Nancy's dog is 3 times as old as Susie's dog"

HENCE FROM THE ABOVE STATEMENT
 
N=3S -> (1)
"Both of their dog's ages equal 27 MEANS"

N+S=27; -> (2)

HENCE FROM (1) AND (2) SOLVE FOR N

N=3S ->S=N/3;

SUBSTITUTE THIS IN (2)
->N+(N/3)=27
->4N/3=27;
->N=20.25 YRS OR 20 1/4 YRS