Ok so we know that the angle of a straight line is 180 on both sides
We have to find x.
The sum of 4x+6 and 11x-6 will equal 180
Lets add them together to equal 180
15x=180
Now we divide both sides by 15 to remove the 15
We get x=12
Now lets insert 12 into 4x+6 to get the answer we need
4(12)+6= ABD Angle
48+6=ABD Angle
54=ABD Angle
The answer is 54°