Middle Discount Rate

Cars with mileage between 10000 and 20000 get the 5% discount rate. In the program, this happens when the first relational expression gives a value of true, and the second relational expression gives a value of false. Say, for example, that MILEAGE is 15000 miles.

        true
   ---------------
IF MILEAGE < 20000 THEN
 
          false
     ---------------
  IF MILEAGE < 10000 THEN
    LET DISCOUNT = .1  
  ELSE
    LET DISCOUNT = .05  <---- this statement
  END IF                      is executed

ELSE
  LET DISCOUNT = 0
END IF

The first true means that the true branch will execute. This true branch is a "little program" with its own control structure. That control structure selects its false branch to execute.