Answer:
On a spreadsheet application including MS Excel;
He can select the image and hold down the rotation handle above it while sliding the mouse
Step-by-step explanation:
Manual rotation of a picture or a text box can be performed by selecting the image or text box in MS Word or a spreadsheet application such as MS Excel. With the mouse select the rotation handle of the picture and drag in the direction desired, left or right.
So as to limit the rotation to 15 degrees hold down the shift button while dragging the rotation handle by clicking on it with a mouse and dragging in the desired direction