The question is an illustration of proportion and exponents
The number of dvd is one crate is: 
From the question, the given parameters are:
<em />
<em> ---- 5 dvds in 1 package</em>
<em />
<em> --- 5 packages in 1 box</em>
<em />
<em> --- 5 boxes in 1 crate</em>
<em />
The number of dvds in 1 crate is calculated as follows:

Substitute 5 packages for 1 box in the above equation

Substitute 5 dvds for 1 package in the above equation

Apply law of indices

Express properly as:

Rewrite as:

Hence, the number of dvd is one crate is: 
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