Es número c por qué esa es la respuesta
The formulas for conditional probability are:


.
Since

and

, you have the equation

.
Therefore,

.
Answer: The correct choice is D.
The final answer should be -49/168.
Answer:
15 early tickets were sold and 5 regular tickets were sold.
Step-by-step explanation:
Let x be the number of early bird tickets sold and y be the number of regular tickets sold.
Total number of tickets sold = 20
Thus, we can write the equation,

Cost of early bird ticket = $10
Cost of regular tickets = $15
Total cost = $225
Thus, we can write the equation,

We solve the equation by elimination method by multiplying first equation by 10 and subtracting.

Thus, 15 early tickets were sold and 5 regular tickets were sold.