Let's first draw a diagram of the situation
Let's call the missing angle a, then using the definition of the sine function, we have that
[tex]\sin (a)=\frac{75}{120}[/tex]then, we can take inverse sine in both sides of the equality to clear a
[tex]a=\sin ^{-1}(\frac{75}{120})=38,68218745[/tex]and rounding to the nearest degree, the answer will be 39 degrees.