Which points are reflections of each other across the y-axis? (–7, –3) and (7, –3) (–5, 4) and (5, –4) (1, –8) and (1, 8) (–3, 5) and (5, –3)

For this case what you should know is that a reflection on the axis y is given by the following rule:
 (x, y) = (- x, y)
 We have then that the points that fulfill that rule are:
 (-7, -3) and (7, -3)
 
 Points that are reflections of each other across the y-axis are:
 (-7, -3) and (7, -3)