b^2/12/(b/4/5/b)

To simplify the expression b^2/12/(b/4/5/b), let's break it down step by step:

Step 1: Simplify the denominator
Since the denominator contains divisions, we need to simplify it from left to right.

b/4/5/b can be rewritten as (b/4) * (1/5) * (1/b).
The b in the numerator and denominator cancels out, and the resulting denominator is (4 * 5) = 20.

Now the expression becomes b^2/12/20.

Step 2: Simplify the division
To divide by a fraction, we can multiply by its reciprocal. In this case, we need to divide b^2/12 by 20, which is equivalent to multiplying by 1/20.

The expression can be rewritten as: b^2/12 * (1/20).

Step 3: Simplify further
Now, we just need to simplify the multiplication of fractions.

To multiply two fractions, we multiply the numerators and multiply the denominators.

b^2 * 1
------------ (notice that 12 and 20 share a common factor of 4)
12 * 20

Simplifying gives us:
b^2
------
4 * 5

This can be further simplified by simplifying the numerator and denominator separately.

The numerator, b^2, does not have any like terms to simplify.

The denominator, 4 * 5, equals 20.

So, the final simplified expression is: b^2/20.

In summary, the expression b^2/12/(b/4/5/b) simplifies to b^2/20 by following the steps of breaking down the denominators, simplifying divisions, and then simplifying the multiplication of fractions.