Answer:
J= 16.857°
K= 88 .4°
L=74.7°
Explanation:
let x represent the angle of J
x° +(4x+21)° +(2x+41)° =180°
x + 4x + 21 + 2x + 41= 180° ( sum of angles in a triangle)
Collect like terms
 x + 4x + 2x = 180 - 21 - 41
7x = 180
x =180/7
x=16.857
 Therefore,
 J = 16.857°
 K=4x+21
 =4(16.857)+21
 = 67.4+21
 =88.4°
L=2x +41
 =2(16.857)+41
 =33.7+41
 = 74.7°
Sum of angles in the triangle = 
16.857+88.4+74.7=179.9 approximately 180°
Hope this helps....