Yes, AB and CD are parallel.
Let's call the angle at the very top of the triangle E.
AEB is a triangle with sides of 6, 9, and the unknown AB.
CED is a triangle with sides of 16 (10+6), 24 (15+9), and the unknown CD.
If you look closely at side AE (6) in relation to side EB (9), you'll notice that the sides are in a ratio of 2:3 (6:9 divided by 3).
Looking now at CE (16) to ED (24), we can see, again, that the sides are in a ratio of 2:3 (16:24 divided by 8).
Because the triangles have the same ratio of side lengths for two sides, the last side (CD and AB), must be in the same proportional ratio to each other.
The two triangles (AEB and CED) are thus proportional triangles.
Angle E is shared between the two triangles (it is at the top).
Thus, we can conclude that AB must be parallel to CD.
