Ado is four times as old as his sister Amina, if the sum of their age is 20 years find the difference of their age

Answer 1

y = 4 x
x + y = 20
so
5 x = 20
x = 4
y = 1 6
16 - 4 = ?

Answer 2

Let Amina's age=x
Ado=4x
x+4x=20
5x=20
x=4
thus, Amina is 4 years old and Ado is 16 years old
16-4=12 years