Si yo tengo una tienda y el día de hoy ay un descuento de 1/4de su precio original y unos niños quieren comprar un camiseta de75,00 cuanto se descontara la camiseta

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Consider u = {x|x is a negative real number}which is an empty set? o {x|x eu and x has a negative cube root}o {x|x eu and x has a negative square root}{x|x eu and x is equal to the product of a positive number and -1}{x|x eu and x is equal to the sum of one negative and one positive number?