Question 1203881
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For this super-simple primitive problem, the solution in one line fits very well


<pre>
    the number of songs = {{{(25-4)/0.05}}} = {{{21/0.05}}} = {{{2100/5}}} = 420.       <U>ANSWER</U>
</pre>

Solved.


The formula is SELF-EXPLANATORY.


Look in it attentively - it will tell you the whole story.