Answer:
Ebony's brother is x + 4 years old.
Ebony's mum is 3x years old.
Explanation:
Since Ebony is x years old, and her brother is 4 years older than her, the expression is x + 4, as her brother is +4 years older.
Ebony's mum is 3 times Ebony's age, which is x. 3 times x is shortened into 3x.