If leah is 6 years older than her sister, sue, and john is 5 years older than leah, and the total of their ages is 41. then how old is sue?

Let us assume the age of Sue = x years
Then
Age of Leah = x + 6
Age of John = 5 + (x + 6)
                    = x + 11
Total of their ages = 41
So
x + x + 6 + x + 11 = 41
3x + 17 = 41
3x = 41 - 17
3x = 24
x = 24/3
   = 8 years
So Sue is 8 years old.