Answer:
36 feets
Step-by-step explanation:
The dimension of bulletin board = 7 feets by 11 feets
Bulletin boards are shaped as a rectangle :
To add a black border ; two of the sides will be of length 7 feets (length) while the other 2 will be of 11 feets (width) each or vice-versa
However, total Lenght of black border :
(11 * 2) + (7 * 2)
22 + 14
= 36 feets
