So first let's convert your words into an actual dataset.
data have;
  input major $60.;
cards;
computer science and enginnering
math and english
science and math
math
english
;
Now we can start writing some code to try to solve the problem.
data want;
  set have;
* Copy the data so SAS will guess that you want MAJOR1 and MAJOR2 defined 
  as the same type and length as MAJOR
;
  major1=major;
  major2=major;
* Check if the word AND appears ;
  location=findw(major,'and',' ','i');
* Split when found ; 
  if location then do;
    major1 = substr(major,1,location-1);
    major2 = left(substrn(major,location+4));
  end;
  else major2=' ';
run;

 
PS Clearly there aren't any English majors as they don't know how to spell ENGINEERING or MATH.