Samurai Burger

My family and I love Samurai Burger from McDonalds and we have Samurai Burger weekly since its launch. However, I seem to pay a different price each time we order the Samurai Burger set meals. It was only when I asked a counter staff today that the truth of the pricing of the Samurai Burger became known to me as follows:


a) Samurai Burger (single patty): $5
b) Samurai Burger set meal (single patty) with regular coke and fries: $6.50
c) Samurai Burger set meal (single patty)with regular coke and fries upsized: $6.50 +$0.50= $7
d) Samurai Burger set meal (single patty)with green tea and fries upsized: $7.45
e) Samurai Burger set meal (Double patty)with green tea and fries upsized: $9.30

I always thought that a Samurai Burger set meal comes with a green tea and it costs $7.45; little do I know till now that this same set meal can be ordered for $7.00 if we do not take the green tea but have the regular coke instead.