Question 883378
w = breadth of original room;
L = length of original room;
L=w+3.


Original room
w and L, area is wL.


New room
L+3 and w-2, area is (w-2)(L+3).


The two rooms were equal area.  The two equations for this system are {{{highlight(wL=(w-2)(L+3))}}} and from the written problem description, {{{highlight(L=w+3)}}}.  Substitution for L allows to solve first for w.