For a trapezoid, if the upper bottom is reduced by 2.5 cm, it becomes a triangle, and the area is reduced by 8.5 square cm compared with the original trapezoid; if the lower bottom is reduced by 4 cm For a trapezoid, if the upper bottom is reduced by 2.5 cm, it becomes a triangle, and the area is reduced by 8.5 square cm compared with the original trapezoid; if the lower bottom is reduced by 4 cm, it becomes a parallel polygon, and the area of the original trapezoid is calculated

For a trapezoid, if the upper bottom is reduced by 2.5 cm, it becomes a triangle, and the area is reduced by 8.5 square cm compared with the original trapezoid; if the lower bottom is reduced by 4 cm For a trapezoid, if the upper bottom is reduced by 2.5 cm, it becomes a triangle, and the area is reduced by 8.5 square cm compared with the original trapezoid; if the lower bottom is reduced by 4 cm, it becomes a parallel polygon, and the area of the original trapezoid is calculated

Your questions are incomplete

A trapezoid, if the upper bottom is reduced by 1.8 cm, will become a triangle, the area is 5.4 square cm less than the original trapezoid; if the upper bottom is increased by 2.6 cm
It becomes a parallelogram. The area of the original trapezoid is ()

The original trapezoid is 1.8 cm long
The length of the original trapezoid is 1.8 + 2.6 = 4.4cm
Height of original trapezoid = 5.4 * 2 / 1.8 = 6cm
Area of original trapezoid = (1.8 + 4.4) * 6 / 2 = 18.6 square centimeter

A trapezoid bottom reduced by 2.5 cm to become a triangle, the original trapezoid area reduced by 20 square centimeters
Find the area of the original trapezoid

20*2÷2.5=16（cm）
I can only come up with this condition. I can't do it