The two sides of a square have the same length. One side increases 16 cm, and the other side decreases 1 1 cm.

So now the difference between them is11+16 = 27 cm.

At this time, the lower bottom surface of the trapezoid is four times that of the upper bottom surface,

The upper bottom is one copy, then the lower bottom is four copies, and the difference between them is three copies.

Three copies are equivalent to 27cm, so the upper bottom of one copy is 9 cm long.

So the bottom is 9*4=36 cm.

Height means that the side length of the original square is 9+ 1 1 = 20cm.

S=(a+b)h÷2=(9+36)*20/2=450 square centimeters.