Hello there. To solve this question, we'll have to remember some properties about trapezoids.
Given a trapezoid with larger and smaller bases B and b, respectively, and height h (being the orthogonal projection of one of the bases onto another) as follows:
Its area A is given by the formula:

In the case of the question, we have a trapezoid with bases measuring 20 cm, 6 cm and height measuring 10 cm.
Plugging the values in the formula, we get:

This is the area of this trapezoid.