Question 1005797
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Do it for each matrix element: calculate  {{{2*A[i,j]}}} - {{{4*B[i,j]}}}  for each pair of indexes  [i,j], i = 1 ,2 3;  j = 1, 2, 3.


Here  {{{A[i,j]}}}  is the element of the matrix  A  at the intersection of the  i-th horizontal row and  j-th vertical column. 

Similar for  {{{B[i,j]}}}.


For instance,  {{{A[1,2]}}} = -8,   {{{B[1,2]}}} = -7,   and 


{{{2*A[1,2]}}} - {{{4*B[1,2]}}} = 2*(-8) - 4*(-7) = -16 + 28 = 12.