A square of area 121 ft² will have a side dimension of √121 ft = 11 ft. The perimeter is the length of 4 sides, so is 44 ft.
I am not familiar with "brighten" but this is how you can expand and use the distributive property:
7(256)
= 7(200 + 50 + 6)
= 7(200) + 7(50) + 7(6)
= 1400 + 350 + 30
= 1780
I have a photo that shows how I got the answer and what the answer is (Key: Red represents my work, while highlighter shows what the answer is):