15%=0.15
6000×0.15=900
He paid $900 (15% of $6000; 6000×0.15=900)
$6000-$900= $5100
and he still have to pay $5100
I believe it is 56 because 7•8 is 56 and 1•56 is 56
Given:
The matrix multiplication

To find:
The order of resulting matrix.
Solution:
We know that, if order of first matrix is
and the order of second matrix is
, then the order of these two matrices is
.
We have,

Here, the order of first matrix is
and the order of the second matrix is
. So, the order of the second matrix is
. It is also written are 2 by 1.
Therefore, the correct option is A.