[tex]5(u + 1) - u = 3(u - 1) + 7 \\ 5u + 5 - u = 3u - 3 + 7 \\ 5u - u + 5 = 3u - 4 \\ 4u + 5 = 3u - 4 \\ 4u - 3u = - 4 - 5 \\ u = - 9[/tex]
sorry if this is not correct
