Need excel help with this kind of calculation as in shown image

Hi ,

I have done one calculation as shown in image below
i want to make excel so that i can get answer directly
after i put 4 numbers
in one excel **** both way i want as show in image
straight and cross calculation
can anyone do it ?
and 498 number is in between will be same always
offcourse it will need alot of brain here
and i am not having it so i want you guys to help me