Answer
The function is one-to-one.
Its inverse is:
$r^{-1} =\left\{(2, 1), (4, 3), (6, 5), (7, 6)\right\} $
Work Step by Step
Every second coordinate is paired with only one first coordinate.
Thus, the function is one-to-one.
The inverse of the function is:
$r^{-1} =\left\{(2, 1), (4, 3), (6, 5), (7, 6)\right\} $