The image displays a black Casio fx-991EX CLASSWIZ scientific calculator positioned on a light-colored surface

The image displays a black Casio fx-991EX CLASSWIZ scientific calculator positioned on a light-colored surface. The calculator's screen indicates the input "90x20" and the computed result "1800". Minor wear is discernible on the calculator's silver directional pad buttons. To the right of the calculator, a white sheet of paper is partially visible, featuring printed Spanish text. Visible segments of the text include "...hay dos formas de calcular la...", "...en el eje X entre el precio del...", "...la fórmula de pendiente vista...", "...de café y cono de helado que maximizan...", and "...ción presupuestal es tangente a la curva". Handwritten notation showing " = -150 / 90" is also present on the paper. A dark grey object is partially visible behind the calculator in the upper left quadrant. An orange-brown object, resembling a cup or container, is partially visible in the upper right background. The scene is situated in Monterrey, Mexico. No individuals are present.