In this question , we have to find the postulate that is illustrated for the real numbers

The postulate is Additive inverse postulate which states that

Where a is the real number and -a is the opposite of a. It states that , if opposite of a number is added with the number, the result is 0 .
I can’t see it it too blurry
Original price×(1-discount price)=new price or sale price so
Put x in original price...x(1-45/100)=550
So the original price is 1000