To answer this question, you first need to know what SohCahToa is.
S- opposite over hypotenuse
C- adjacent over hypotenuse
T- opposite over adjacent
In this situation, they have made it easier for you as they have given you the quotient of the opposite and adjacent sides (3.4) . Now in order to find an angle, you take the inverse of your expression. So instead of just Tan, you would plug in Tan^-1. So plug it in:
Tan^-1 (3.4)
Answer is 73.6 degrees.