Supermarket sweep

He has to shop for grocery today as it is Tuesday and there is a special 10% cash rebate just on Tuesday. On other days, it is just 5% cash rebate. Recently, his wife applied for a supplementary card for him just so that they could get to enjoy this savings. A few days before, he made a long list of things that he has to get for the household. He estimated that it would take him at least 2 hours to get all the things on his list. Just 1 hour into his shopping, his phone rang and it was his son, Wen Kok's primary school teacher. The teacher told him that his son is not feeling well and wants to go home. So can he please go over and pick him up as soon as he can? Well, his shopping is not done yet but his son is his priority. He rushed around the supermarket and basically just grabbed the things on his list. Paid up and went to get his son. Miraculously, his son felt much better in his car and they went to have lunch together at Esquire Kitchen. At home, when he was putting away the things he bought into the cabinets, he discovered that in his hurry, he has bought a new 750ml bottle of shampoo at an expensive price of RM30 when there is still a full bottle, unused in the cupboard. There are times that the bottle of shampoo is sold at a cheaper price of RM19. The wife is not going to like this.