Answer:

Step-by-step explanation:
One type of transformation is rotations, which are done counter-clockwise direction.
In this case, we have a rotation of 90° around the origin (0,0), that can be expressed as

Which means a 90° rotation would be done by changing coordinates positions and inverting the sign of y-coordinate.
However, the problem is giving the transformed coordinates where
.
So, applying the rule described above, the original coordinate is
.