Finished Program

 
'Calculate cost of fuel
'depending on grade and gallons
'
PRINT "How many gallons"
INPUT gallons
PRINT "What grade (R, E, or S)"
INPUT grade$
'
'Calculate cost
'
IF  grade$ = "R" THEN
  PRINT "Cost is", 1.2 * gallons, "dollars"

ELSEIF  grade$ = "E"  THEN
  PRINT "Cost is", 1.3 * gallons, "dollars"

ELSEIF  grade$ = "S"  THEN
  PRINT "Cost is", 1.4 * gallons, "dollars"

ELSE
  PRINT "You entered an incorrect grade"

END IF

END