You can
put this solution on YOUR website!A 100% increase means it is doubled
If the sides of the rectangle are

and

, the area,

is
(1)

Doubling each side gives me

(2)

Comparing (1) and (2),

If the dimensions of a rectagle are increased 100%,
The area is increased 400%
You can
put this solution on YOUR website!
original:

,

sq.units
If increased by 100%
New:

,

sq.units ---> increased by 4 times
.
Another sample:
original:

;

sq.units
If increased 100%
New:

;

sq.units ----> increased by 4 times
.
Another sample:
original:

;

sq.units
If increased 100%
New:

;

sq.units ---> increased by 4 times
.
Therefore, if that's the case when dimensions are increased 100%, then the New Area will be increased

as you see.
Thank you,
Jojo