Explanation

The entire part of bucket water quantity is 1.
So that, \left(1-\large\frac{4}{5}\right) part of the bucket weighs =\left(30-26\right) kg.
\rightarrow \large\left(\frac{5-4}{5}\right) part of the bucket water weighs = 4 kg
\rightarrow \large\frac{1}{5} part of the bucket water weighs = 4 kg
\therefore 1 or full bucket water weighs =\left(4\times\large\frac{5}{1}\right) kg
\rightarrow 20 kg.
But, according to the question, completely filled with water bucket weighs is 30 kg.
So that, the empty bucket weighs is =\left(30-20\right) kg
\rightarrow 10 kg.
Ans: The empty bucket weighs is 10 kg.

An additional variation of this particular math query can be considered:

1. Find out the weight of the empty bucket when partially filled with water, with known weights of 30 kg when full and 26 kg when 4/5 full.
2. Calculate the weight of an empty bucket when filled with water, given that it weighs 30 kg when full and 26 kg when 4/5 full.
3. Calculate the weight of the empty bucket based on its weights when full and 4/5 full, with known values of 30 kg and 26 kg respectively.
4. What is the weight of the empty bucket when filled with water, given that it weighs 30 kg when full and 26 kg when 4/5 full?