Answer:
x=-5/3
Explanation:
ABD + DBC = ABC
Substitute the values
6x+9 + x+1 = 10x+15
Combine like terms
7x+10 = 10x+15
Subtract 7x from each side
7x-7x+10 = 10x-7x+15
10 = 3x+15
Subtract 15 from each side
10-15 = 3x+15-15
-5 =3x
Divide each side by 3
-5/3 =x
This will give us a negative value for DBC
DBC = -5/3 +3/3 = -2/3
We cannot have a negative value for an angle
Check the values given.