Final answer:
To find the number of adult tickets sold, we set up a system of two equations based on the total tickets sold and the total revenue. After simplifying, we found out that 80 adult tickets were sold.
Step-by-step explanation:
The subject of this question is to determine the number of adult tickets sold, based on the given revenue and ticket prices.
To find the answer, let's denote the number of adult tickets as A and the number of student tickets as S. We know that A + S = 120 tickets in total were sold.
The total revenue from ticket sales was Birr 8400, so we set up the equation: 80A + 50S = 8400.
Now we use the first equation to express S in terms of A: S = 120 - A.
Substituting into the second equation, we get: 80A + 50(120 - A) = 8400, which simplifies to 80A + 6000 - 50A = 8400, or 30A = 2400.
Solving for A, we get: A = 2400/30 = 80.
Therefore, 80 adult tickets were sold.