a=AB, b=BC, c=CD, d=DA, e=AC, f=BD, u=angleADB

Let a=1. Angles ADC and ABC are both = 60 degrees...see that?

4 steps:

1: calculate e using triangleABC and Sine Law

2: calculate d using triangleACD and Sine Law

3: calculate f using triangleABD and Cosine Law

4: calculate u using triangleABD and Sine Law.

At this point, you should be using: a/SIN(u) = f/SIN(130)

There's probably a more elegant non-trigonometric solution,

but I'm too lazy to give it a shot!!