Question 1198564
Rs 120 per dozen = Rs 120 per 12 each = Rs 10 each

<pre>
CONDITIONS    PRICE         QUANTITY        COST
Normal        1680/n         n              1680
Unfair        1680/(n+4)     n+4            1680
Difference     10
</pre>
The price difference for each passion fruit was Rs 10.
{{{highlight_green(1680/n-1680/(n+4)=10)}}}


{{{168/n-168/(n+4)=1}}}

{{{168(n+4)-168n=n(n+4)}}}

{{{168*4=n^2+4n}}}

{{{n^2+4n=168*4}}}

{{{n(n+4)=7*24*4}}}

{{{n(n+4)=24*28}}}


The normal and fair quantity was 24 passion fruit.
Person telling the story achieved  28 passion fruit.