Answer and step-by-step explanation:
The formula for the area of a trapezoid is

Substituting 100 in for A,

Cancel the 1/2 by multiplying both sides by 2:

We want the sum of the bases multiplied by the height to be 200.
If we let the height be 10, this would make the sum of the bases 200/10 = 20.
Any two numbers that sum to 20 will work; we can use 7 for the smaller base and 13 for the larger one.