Howdy!
The answer is A, Between 2 and 3. To find this out, multiply 6(/1) by 2/5, which is 2.4, 2.4 is between 2 and 3, so that's the answer.
Hope this helped!
The first is a. you can rewrite it

the second is d. the only common factor between 20 and 40 that can be taken out is the 4 which becomes a 2, but inside the square roots there is still a 5 and 10, which cannot be combined
the third is c.

the fourth is d.
add 3 to both sides

then square both sides

then divide both sides by 2, x=50
Answer: 576 inches or 48 feet
Step-by-step explanation:
set up a proportion where 
so you get drawingAB = 24 in
actualAB = 18 feet = 18 * 12 in = 216 in
drawing perimeter = 64 in
so plug these in to get
rearrange to get 
and solve to get 576 inches or 576/12 = 48 feet
Let x be the shorter side, and y be the longer side
There would be 4 fences along the shorter side, and 2 fences along the longer side
4x + 2y = 800
Rewrite in terms of y:
y = 400 − 2x
The area of the rectangular field is
A = x*y
Replace Y with the equation above:
A = x(400 − 2x)
A = − 2x^2 + 400x
The area is a parabola that opens downward, the maximum area would occur at the parabola vertex.
At the vertex
x = −b/2a
= −400/[2(−2)]
= 100
y = 400 −2x
y = 400 -2(100)
y = 400-200
y = 200
The dimension of the rectangular field that maximize the enclosed area is 100 ft x 200 ft.