Let x be the number of years for the Cara to be triple of her brother's age.
Brother = 4 years old
Cara = 8 years old
8 + x = 3(4 + x)
8 + x = 12 + 3x
3x - x = -4
2x = -4
x = -2
She was triple his age 2 years ago but she will never to triple his age in the future.
