Final answer:
To find the visible length of the picture after framing, the correct expression would be 7 - (-1/4) which simplifies to 7 + 1/4 inch.
Step-by-step explanation:
Keesha wants to find the length that is still showing on a picture after placing it in a frame which hides 1/4 of an inch of the picture on each side. The correct expression to find the visible length of the picture is 7 - (-1/4). This is because the frame hides 1/4 inch, so we subtract a negative number, which is the same as adding. Therefore, the visible length would be 7 + 1/4 inch.