Transform an object relatively
Relative transformations in Microsoft Expression Blend enable you to transform objects relative to the current state of the object, and apply the same transformation repeatedly. For example, after you set an initial transform value (for example, a rotation angle of 15 degrees), you could animate the object by repeatedly moving the timeline playhead and clicking the Apply button in the Transform category of the Properties panel to set a keyframe. When the animation timeline runs, Expression Blend rotates the object 15 degrees relative to the object's rotation angle at the previous keyframe.
Select the object that you want to transform, by using either the Selection tool or the Direct Selection tool and then clicking the object on the artboard.
In the RenderTransform category under Transform in the Properties panel, click the appropriate tab (Rotate , Scale , and so on) for the transform that you want to perform.
For information about the RenderTransform and LayoutTransform transform categories, see Moving and transforming objects.
Set the desired transformation values. You can press the TAB key to move from property to property.
Select Use relative values, and then click Apply one or more times.