Figure ABCD is a kite.

Kite A B C D is shown. Sides A B and B C are congruent. The length of A B is 3 x + 1 and the length of B C is 22. Sides A D and C D are congruent. The length of A D is 4 x.

What is the length of line segment CD?

7 units
8 units
28 units
35 units