A matrix is diagonal if

In other words, you want non-zero elements only when the indices of the row and the column are the same: the first element of the first row must be non zero, the second element of the second row must be non-zero, and so on. All other elements must be zero.
The answer is Lisa, because there can be only one answer to the question
Answer:
20 cm^2
Step-by-step explanation:
Sectioned it off and multiplied the length by the width
20 plus 24
Divided by 15
Which gets you to
44 over 15 or 2 wholes and 14 over 15