Is there supposed to be a picture included?
A = cost of 1 drink $12.75 + 4a $12.75 + $12.00 = $24.75
Answer: 90 degrees clockwise
This is equivalent to 270 degrees counterclockwise
The rule for either rotation is 
The x and y coordinates swap places, and the new second coordinate flips from positive to negative (or vice versa).
The diagram below shows an example of this for the point (-4,-2) rotating to (-2, 4). The center of the rotation is the origin (0,0).