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put this solution on YOUR website!Start with defining a variable to represent the length of a side of the original square, let's call it x.
So the area of the original square would be

.
The new square is 2 cm shorter on each side, so one of the sides must measure

, and the area of the new square must be

.
But we know that

. Substituting:

.
Now, expand the binomial, collect terms, and put the equation in standard form.
So the original square was 10 cm on a side.
Let's check the answer.
Original area

New area

, Check.