Determine the matrix of the linear mapping https://webwork.math.su.se/webwork2_...e043270961.png defined by the vector https://webwork.math.su.se/webwork2_...fd8fbc7ea1.png first mapped to https://webwork.math.su.se/webwork2_...c3c12e01a1.png where https://webwork.math.su.se/webwork2_...c42a1ee611.png and then mirrored in the plane https://webwork.math.su.se/webwork2_...5317b0abb1.png. (positively oriented ON-systems).

i got no progress, dont know how to solve it