Answer:
 Angle C is 7 * 18 - 4 = 122 
 Angle B is 18 + 4 = 22 
 Angle D is 2 * 18 = 36
Explanation:
As we know that the sum of all angles of a triangle is 180
So adding all the angles we get 
2x + x+4 + 7x-4 = 180
10x = 180
10x = 180 
 x = 18 
 In order to find each angle, put x = 18. 
 Angle C is 7 * 18 - 4 = 122 
 Angle B is 18 + 4 = 22 
 Angle D is 2 * 18 = 36