Only One Branch is Picked

Remember that with the IF-ELSEIF structure only one branch is picked. The computer starts at the top and goes down the list of conditions until it finds the first one that is true. That determines the one branch that is executed. In this example, AGE < 24 is the first true condition, so its branch is executed:

 
PRINT "Enter full fare" 
INPUT FARE                <-- 100
PRINT "Enter age"
INPUT AGE                 <-- 23
'
'Calculate discount based on age

IF AGE < 12 THEN          <-- false
  LET RATE = 0.0 

ELSEIF AGE  < 24 THEN     <-- true
  LET RATE = 0.70         <-- this branch picked

ELSEIF  AGE < 65 THEN
  LET RATE = 1.0
   
ELSE
  LET RATE = 0.75

END IF

'Calculate fare
PRINT "Your fare is:", FARE * RATE  <-- this statement is done next
END

It is also true that AGE < 65 but this is not the first true condition, so its branch is not picked.