ANSWER
24
EXPLANATION
For a matrix A of order n×n, the cofactor 
of element 
is defined to be
is the minor of element equal to the determinant of the matrix we get by taking matrix A and deleting row i and column j.
Here, we have
M₁₁ is the determinant of the matrix that is matrix A with row 1 and column 1 removed. The bold entries are the row and the column we delete.
Since the determinant of a 2×2 matrix is
it follows that
so 
3.43 look to the number to the right of the hundredths place. If it's higher than 5 round up.
The vertical line test is when you put vertical lines down the graph and if the point does not touch the line more than once, it passes and represents a function.
Answer:
D
Step-by-step explanation:
The answer is d, because a represents adults, and c represent children. It's $45 per adult, so $45a, and $30 per child, so $30c. a+c is equal to 10, because that's how many tickets were purchased. $45a+$30c=345, because $345 is the total amount spent on tickets.
It should be the first answer choice between those two
