If then

Hi

I have  to created calculated column where the condition is below:

If field A is null, then compare  AMT1 = AMT2= AMT3 then say EQ  else NE

if field A is not null then compare AMT1 = AMT2= AMT3= AMT4.

How to write the formula ?

I tried by splitting in two columns as  test 1=  if(AMT1 = AMT2,"AMT1",'NE')

                                      test 2 =if(if(AMT3 = AMT4,"AMT3",'NE')

then CA= IF( Is NULL("A") = 1,if(test 1 = amt3,'E',IF( test 1 = test 2,'EQ','NE'). but getting error. Is it a good practice  to split up?

i tried like

IF( Is NULL("A") = 1,if(AMT1 = AMT2 and AMT3,'EQ',ifAMT1 = AMT2 and AMT3 and AMT4,'EQ','NE

both ways i am getting error.