Rotation Help

Fellow math nerds: help me out here. I was describing how to rotate a figure 270 degrees clockwise to someone. I told them to reflect the figure over the y-axis, then switch the coordinates to fix the orientation. They told me this was the formula for rotating a figure 90 degrees counterclockwise. Well, yeah. . . . what's the difference? Is there a different formula you're supposed to use for a 270 degree clockwise rotation vs. a 90 degree counterclockwise rotation? I'm at a loss. . .