Answer:
MJ = 9
Step-by-step explanation:
Since JK is parallel to MN and MN intersects the 2 sides, then MN divides the 2 sides in proportion, that is
[tex]\frac{LM}{MJ}[/tex] = [tex]\frac{LN}{NK}[/tex], substitute values
[tex]\frac{12}{MJ}[/tex] = [tex]\frac{20}{15}[/tex] ( cross- multiply )
20MJ = 180 ( divide both sides by 20 )
MJ = 9
