each cell size =$4$ words
array size =$25*4$
Data Stored in row major order.
We need array[12,3] address .
So we first have to cross all the element till 11th row . As each row has $4$ column so total no of element we crossed $4*12=48$ [considering array index start from 0th row so , $0$ to $11$ total $12$ rows each having $4$ elements].
Now we are at 12th row and we have to go to 3rd column 12th row so we have to $3$ element in that row .
So total number of element we crossed =$(48+3)=51$
Each element size =4 word .
So crossed =$51*4=204$
Base address =$200$
So the address of the cell array[12,3] =$200+204=404$.