Solve by elimination. 2x+3y=20 and -2x+y=4 how do i do it? ?

What are the domain and range of the function? f(x) = -4 (sqrt)x

Lucy is a dress maker. she sews \dfrac47 7 4 of a dress in \dfrac34 4 3 hour. lucy sews at a constant rate. at this rate, how many dresses does lucy sew in one hour? include fractions of dresses if applicable

What are the solutions of the system? solve by graphing. y = -x^2 -6x - 7 y = 2