2 arcsin(-1/2) + arctg(-1) + arccos (√2/2)

First, let's find the values of each of these trigonometric functions:

arcsin(-1/2): The value of sin(-30°) is -1/2, so arcsin(-1/2) = -30°.

arctg(-1): The value of tan(-π/4) is -1, so arctg(-1) = -π/4.

arccos (√2/2): Since the value of cos(π/4) is √2/2, arccos (√2/2) = π/4.

Therefore, the expression becomes:

2*(-30°) + (-π/4) + π/4
= -60° - π/4 + π/4
= -60°

So, the final answer is -60°.