Answer:
Her son is 10 years old.
Step-by-step explanation:
Let son be x
Ellie is 4x
In 5 years time: Her son = x + 5
Ellie = 4x + 5
Given that she will then be 3 times as old as her son: 4x + 5 = 3(x + 5)
Solve x: 4x + 5 = 3(x + 5) ,4x + 5 = 3x + 15
x = 10
