The problem statement tells you ∠MLK is 61°, so ∠LMK = 180° -68° -61° = 51°. Since a tangent is always perpendicular to a radius, triangles LJM and LJK are right triangles.
Trigonometry tells you ...
tangent = opposite / adjacent
so you can write two relations involving LJ.
tan(51°) = LJ/JM
tan(68°) = LJ/JK
The second equation can be used to write an expression for LJ that can be substituted into the first equation.
LJ = JK*tan(68°) = 3*tan(68°)
Substituting, we have
tan(51°) = 3*tan(68°)/JM
Multiplying by JM/tan(51°), we get
JM = 3*tan(68°)/tan(51°)
JM ≈ 6.01
The radius of circle M is about 6.01.
