Stephanie is 6 years old, and her sister is 13 years old.
To solve this, we can set up a system of equations:
Let Stephanie's current age be s.
Her sister's age is then s + 7 (since she's seven years older).
Their combined age is given as 19.
Therefore, we have the equation:
s + (s + 7) = 19
Combining like terms:
2s + 7 = 19
Subtracting 7 from both sides:
2s = 12
Dividing both sides by 2:
s = 6
Now that you know Stephanie's age is 6, her sister's age is simply:
s + 7 = 6 + 7 = 13
Therefore, Stephanie is 6 years old, and her sister is 13 years old.