Answer:
The perimeter is 
Step-by-step explanation:
we know that
The perimeter of the figure is equal to the circumference of a semicircle
plus the perimeter of a square minus the diameter of the circle
so

we have



The diameter of the circle is equal to the length side of the square
substitute



The area of the dock is 20ft
Order of operations (PEMDAS):
21 - 18 <span>/ 3 * 2
let's add some parenthesese to make it easier to see:
21 - (18 / 3 * 2)
multiplication and division are associative
also: 18 / 3 = 18 * (1/3)
21 - (18 * (1/3) * 2)
21 - (6*2) or 21 - (36 * (1/3)) or 21 - (18 * (2/3))
21 - 12
9
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