Answer:
120
Explanation:
The sum of the angles is 180 since it forms a straight line
2x+ x+90 = 180
Combine like terms
3x +90=180
Subtract 90 from each side
3x+90-90=180-90
3x= 90
Divide each side by 3
3x/3 = 90/3
x = 30
We want angle DBC = x+90
= 30+90
=120