'    This exercise shows how you can check to see if either of
'    two conditions are true.
'                                       _______
' A program is required to calculate  \/ a - b
'                                     ----------
'                                          a
' This cannot be done if a < b , or if a = 0 (Think about it).
' Fill in the missing parts of the program below.
' Test it with the following sets of data.
'       a       b    
'       4       2
'       2       4
'       0       4

input "Give me a value for a: ",
INPUT "What is b"; b
IF  ???  OR ??? THEN
    PRINT "I cannot do the calculation"
ELSE
    LET  answer =
    PRINT "The answer is: "???
END IF