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Is a currency whose value is tied to another currency, meaning that the exchange is fixed

What is the value of  y  in the solution to the system of equations? x  +  y  =  12x  –  3y  =  –30a. –8b. –3c. 3d. 8

Plz need answer now will mark which situations represent linear functions? check all that apply. a)the temperature rises and falls over the course of a day. temperature is a function of time. b)a baseball is hit into the outfield. the height of the ball is a function of time. c)a car goes 55 mph on the highway. distance is a function of time. d)a child grew 2 inches this year and 1 inch last year. height is a function of time. e)a movie director makes 2 movies per year. the number of movies is a function of the years.