Explanation

Let's simplify the expression:

log6 25 − 2 log6 5 + log6 a

Since 25 = 5^2:

log6 25 = log6 (5^2) = 2 log6 5

So, the expression becomes:

2 log6 5 - 2 log6 5 + log6 a

= log6 a

If this expression equals 0 (assuming that's the goal):

log6 a = 0

This implies:

a = 6^0

a = 1