Try this solution:
1. rules:

2. according to the rule described above:
Answer:
an= 12 + (-6)(n-1)
Step-by-step explanation:
you should find two values: a1 and d
a1= first number =12
d= a number of the sequence mines the number of the sequence before the one you chose = 0-6 = -6
a1+(n-1)d= 12-6(n-1)
Answer:
The width will be 
Step-by-step explanation:
Thinking process:
Let the model be:

factoring out 4 gives:

Factorizing the expression in the parentheses gives:

Therefore, since the expression in the parentheses cannot be factorized further, the expression is:

Answer:
$48
Step-by-step explanation:
Each ticket costs 4 dollars.