52. In the figure below, line q in the standard (x,y) coordinate plane has equation −2x + y = 1 and
intersects line r, which is distinct from line q, at a point on the x-axis. The angles, ∠a and ∠b, formed by
these lines and the x-axis are congruent. What is the slope of line r ?

  • F. −2

  • G. – 1/2

  • H. 1/2

  • J. 2

  • K. Cannot be determined from the given information