Can someone help me on this

29 degrees

Step-by-step explanation:

angle ABD = (x + 9) degrees

angle DBC = (2x - 19) degrees

angle ABC = angle ABD + angle DBC

50 = (x + 9) + (2x - 19)

= 3x - 10

3x = 50 + 10

x = 60/3

x = 20

Substitute x = 20 into angle ABD = (x + 9)

angle ABD = 20 + 9

angle ABD = 29 degrees

a) one student is chosen from classroom a, then a student is chosen from classroom b.  

step-by-step explanation:

independent events are ones in which the probability of one event does not affect the probability of the second event.

one student is chosen from classroom a; this does not affect the chances of choosing a student from classroom b.   this makes these independent events.

when one card is chosen from a standard deck and then set aside before a second card is chosen, the probability of the second card being chosen changes.   this makes them dependent events.

when one student is chosen from classroom a and then a second student is chosen from classroom a, the probability of choosing the second student changes.   this makes them dependent events.

when a letter is chosen from the alphabet and then a second letter is chosen, the probability of choosing the second letter changes.   this makes them dependent events.