Logic, fallacy, the illusion of saving

When the words or the mind cheat wrong or hasty decisions?

Among the formal arguments, the modus ponendo ponens (or modus ponens, MP) is one of the best known. The MP is a valid argument form and an inference rule in propositional logic. The statement is: "If P implies Q, and P is true, then Q is also true."

In the MP it is based on a conditional (if A, then B), the first or antecedent A is given or affirmed, and it is concluded that the consequent or B e true.

If A, then B. A. Therefore, B.

The invalid fallacy or reasoning would be:

If A, then B. B. Therefore, A.

Now, thinking about the World Cup, you go through an electrical appliance store and see a beautiful flat screen TV. The seller notices your interest, tells you it costs $ 1,000 but if you buy it now you only have to pay $. 750. And it surely tells you that you save $ 250.

What would be the valid argument for you?

First: If I pay $ 750 for the television, then I save.

I pay $ 750 per TV.

Then, this saving.

Second: If I pay $ 750 for the television, then I save.

I'm saving.

Then, I paid only $ 750 for the TV