Let x be the degree of angle a.
Angle b: 20+3x
Angle c: 55+x
We know that all angles add up to 180 degrees.
180=x+(20+3x)+(55+x)
180= 5x+75
180-75=5x
105/5=x
21=x
Angle a: 21 degrees
Angle b: 20+3(21) => 83 degrees
Angle c: 21+55 => 76 degrees
Hope I helped :)
To solve this you want to plug in your x's and y's to see if they match.
A. 3(11)-4=33-4=29 and 29 is not equal to 5 so A is not a solution
B.3(5)-4=15-4=11=11 3(3)-4=9-4=5 and 5 is not equal to 2 so B is not a solution
C. 3(2)-4= 6-4=2 2 is not equal to 3 so C is not a solution
D is the answer. 3(5)-4=11 and 3(2)-4= 2
B I think but i could be totally wrong