Given that the original price is d dollars.
In the store, everything is 75% off.
Adam's expression is
[tex]d-0.75d[/tex]Rena's expression is
[tex]0.25d[/tex]In Adam's expression
d is the original price of the video game.
0.75 is the percent discount.
0.75d is the amount of discount.
d-0.75d is the sale price of the video game.
Now, on simplifying,
[tex]d-0.75d=0.25d[/tex]So, in Rena's expression,
0.25 is the percent of the original price Rena will pay
0.25d is the sale price of the video game
d is the original price of the video game.