help please you have to put an explanation as to why its the answer.

Answer:
12 1/4
Step-by-step explanation:
When you add the widths of the frames together you get 48.5 and subtracting that from 79 gives you 30.5 subtract 6 from that is 24.5 which is divided by2 to get 12.25 which when converted to a fraction is 12 1/4.