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 11^{th} row . As each row has $4$ column so total no of element we crossed $4*12=48$ [considering array index start from 0^{th} row so , $0$ to $11$ total $12$ rows each having $4$ elements].

Now we are at 12^{th} row and we have to go to 3^{rd} column 12^{th} 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] =$200+204=404$.