Final answer:
The number of adult tickets sold the day before the show was D) 96.
Step-by-step explanation:
Let's assume the number of adult tickets sold the day before the show is 8x, and the number of child tickets is 3x, where x is a common multiple. On the day of the show, the theatre sold 30 more adult tickets, so the ratio of adult to child tickets became (8x + 30):(3x). According to the question, this ratio is also equal to 7:2. Setting up an equation:
(8x + 30)/(3x) = 7/2
Now, we can solve for x:
2(8x + 30) = 7(3x)
16x + 60 = 21x
60 = 21x - 16x
60 = 5x
x = 12
So, the number of adult tickets sold the day before the show is 8x = 8(12) = 96.