Question 823695
Let N = size of original group.


The 1-person share is {{{900/N}}}  dollars per person.
If two more people, then N+2 is the number of people to share.  The 1-person share would be {{{900/(N+2)}}}.  That is a 75 dollar reduction, as {{{highlight(900/N-900/(N+2)=75)}}};


If you understand that analysis and understand and have no trouble accepting the highlighted equation, then certainly solving the equation is of much less trouble...