Answer:

Explanation:
∠ABC and ∠DBC are supplementary which means that the sum of these two angles is equal to 180.
∠ABC + ∠DBC = 180
Given that: ∠ABC = x+30 and ∠DBC = x - 10
So,
=> x+30+x-10 = 180
=> 2x+20 = 180
=> 2x = 180-20
=> 2x = 160
Dividing both sides by 2
=> x = 80
Now, Finding measures of the angles.
=> ∠DBC = x-10 = 80-10 = 70 degrees
=> ∠ABC = x+30 =80+30 = 110 degrees