Explanation:
imagine a circle with J being the center, and JK being the radius.
then
sin(J) = 15.1/JK
cos(J) = 9.4/JK
we have one trigonometric function, where we don't need to calculate JK first : tangent.
tan(J) = sin(J)/cos(J) = 15.1/JK / 9.4/JK = 15.1/9.4 =
= 1.606382978...
J = 58.09705252...° ≈ 58.1°