Question 1058444
Let  a = the oldest girl, b is the younger 
:
the difference of their ages is 5.
a - b = 5
:
 Four years ago, she is 12 years old.
Therefore she (a) is 16 yrs old now
: 
 How old is she now if she is younger than her?
b = a - 5
b = 16 - 5
b = 11 yrs old is the younger