Question 1161741
{{{matrix(7,7,

(matrix(2,1,A,NUMBER)),""-"",expr(1/4)*(matrix(2,1,THAT,NUMBER)),"",""="","",
21,


x,""-"",expr(1/4)x,"",""="","",21

      ,



4*x,""-"",4*expr(1/4)x,"",""="","",4*21

     ,

4x,""-"",x,"",""="","",84

      ,

"","",3x,"",""="","",84


      ,

"","",3x/3,"",""="","",84/3


      ,

"","",x,"",""="","",28 )}}}