Question 896312
There are meters and centimeters in your problem, and centimeters do not make sense, because a floor with a surface area of 120 square centimeters (10 cm by 12 cm for example) belongs only in a doll house.
Even if we did not want realistic measurements, if we start with a floor length that can be made 3 meters shorter, we could start with at 3.01 meters (301 cm), which would require a width of less than 1 centimeter to yield a surface area of 120 square centimeters.
There must be a typo, and the surface area of each floor is supposed to be 120 square meters.
The numbers would be ugly, and I do not think that was intended.
 
Here is the way to solve the reasonable problem.
The floors have a surface area of 120 square meters {{{120}}}{{{m^2}}} .
{{{L}}}= length of the first floor in m (meters).
{{{W}}}= width of the first floor in m.
For the first floor,
{{{L*W=120}}} is how we calculate its area.
The second floor has the same surface area, but its length is less, so its width must be more.
The second floor's length measures 3 meters less, and its width measures 2 meters longer than the first floor, so
{{{L-3}}}= length of the second floor in m,
{{{W+2}}}= width of the second floor in m, and
{{{(L-3)(W+2)=120}}} is the area of the second floor.
{{{(L-3)(W+2)=120}}} --> {{{L*W+2L-3W-6=120}}}
{{{system(L*W+2L-3W-6=120,L*W=120)}}} --> {{{system(120+2L-3W-6=120,L=120/W)}}} --> {{{system(2L-3W-6=0,L=120/W)}}} --> {{{system(2L=3W+6,L=120/W)}}} --> {{{3W+6=2*(120/W)}}} --> {{{3W+6=240/W}}}
{{{3W+6=240/W}}} --> {{{W+2=80/W}}} --> {{{W^2+2W=80}}}
We can easily solve that quadratic equation by "completing the square:
{{{W^2+2W=80}}} --> {{{W^2+2W+1=80+1}}} --> {{{(W+1)^2=81}}} --> {{{(W+1)^2=9^2}}} --> {{{W+1=9}}} --> {{{W=9-1}}} --> {{{W=8}}} .
That would tell us that the the first floor has a width of 8 meters, and a length  (in m) of
{{{L=120/8=15}}} . (Its length is 15 meters).
The second floor would be 3 meters shorter, so it is 12 meters long (15m - 3m = 12m),
and it is 2 meters wider (8m + 2m = 10 m), so it is 10 meters wide.