I did this last year I might be off but here I go:
This is a 60 60 60 triangle equaling 180 degrees, therefore x is 60, we can tell the angles are the same, since LKM is an outer angle you could plug in 60 for x, therefore (3 * 60 - 70).
3 * 60 = 180 - 70 = 110, you can tell this angle is over 90 degrees so this works.
