Since the ages are consecutive integers and if x is one of them, then I can write the following equation:
the 1st age= x-1
the 2nd age = x
the 3rd age = x+1
(x-1) + (x) + (x+1) = 48
3x = 48 and x = 16
the 1st = 15
the 2nd = 16
the 3rd = 17 (the older)
