Someone explain to me how to do this

  14.9 cm

Step-by-step explanation:

The side of interest is opposite an angle that is not marked. You find the value of that angle by making use of the fact that the sum of angles of a triangle is 180°.

  C = 180° -150° -12° = 18°

Now, fill in the available information in the given formula for the Law of Sines and solve for c:

  sin(B)/b = sin(C)/c

  sin(12°)/(10 cm) = sin(18°)/c

Cross multiply:

  c·sin(12°) = (10 cm)·sin(18°)

Divide by the coefficient of c:

  c = (10 cm)·sin(18°)/sin(12°) ≈ 14.9 cm

step-by-step explanation: