Respuesta :

1200 - 450 = 750 liters that he needs to fill up

81.5 x 750 = €61,125 
€61,125 x 0.075 = €4,584.38 (discount as a loyal customer)
total paid with discount = €61,125 - €4,584.38 = €56,540.62

answer
Mr. Leonard gets  €4,584.38 discount on his purchase