Question 622044
To solve this problem, you need to write 3 equations using what you know.
First, you know that Leah is 6 years older than Sue, or Sue's age + 6 equals Leah's age:
L = S + 6 or S = L - 6 (this is the same equation, just rewritten)
Next you know that John is 5 years older than Leah:
J = L + 5
Finally, you know that the total of their ages is 41:
J + L + S = 41

Now you want to get rid of all but one of the unknown values (J,S,L) so you can solve the problem.  This can be done by plugging in the first two equations into the third equation for S and J:
J + L + S = 41
(L + 5) + L + (L - 6) = 41
L + 5 + L + L - 6 = 41
3L + 5 - 6 = 41
3L - 1 = 41
3L = 42
L = 14
So we know Leah's age is 14.  To find out how old Sue is, plug this value into the first equation:
L = S + 6
14 = S + 6
8 = S
So Sue is 8 years old.