The answer is: "123454321"
Hope this helps!
The vertex where the two triangles touch forms a pair of vertical angles, so that the angles on opposites sides of the vertex are congruent. You're shown that two legs of both triangles are congruent. All this tells you that the two triangles are isosceles, and furthermore that they are similar because of the congruence of their "base" angles.
This means




Because this shape has 2 right angles, we can confirm that it has one set of parallel sides and is a trapezoid. Therefore, use the formula for area of a trapezoid, .5(b1+b2)(h)
.5(1+6)(12)
.5(7)(12)
42 units^2
D because you have to distribute the twelve to complete the equation