If you trying to answer what would be on all the sides if it were to be equal then 51 would be the answer if it's not what the question seems I will try and answer, but be more explanatory.
Answer:
А.The system has two solutions, but only one is viable because the other results in a negative width.
Step-by-step explanation:
Given
Let:
length of play area A
width of play area A
length of play area B
width of play area B
Area of A
Area of B
From the question, we have the following:




The area of A is:

This gives:

Open bracket

The area of B is:


Substitute: 

Open brackets


Expand


We have that:

This gives:

Collect like terms


Using quadratic calculator, we have:
or
--- approximated
But the width can not be negative; So:

For the first one write 9 divided by 2 gives your your radius an it’s 3.5. the formula is 2 x 3.14 x radius and that gives you 21.98.
the 2nd one is 2 x 3.14 x 9 = 56.52
the 3rd is 2 x 3.14 x 5= 31.4
formula is always 2 x 3.14 (or pie) x radius
to get your radius from your diameter you do your diameter divided by 2
Let x be the common factor between chickens and ducks. Then:
6x/(5x-63)=3/1
15x-189=6x
9x=189
x=21
6x=123 chickens were on the farm
☺☺☺☺
Ie 32^2 - 4ac=0 so ac=256 and a+c=130
So, that means:2 equations ac=256 a+c=130 ie c=130-a
So,a(130-a)=256 so 130a -a^2=256 ie a^2-130a +256=0 (a-2)(a-128)=0
Finally,giving a= 2 or a=128 so, a=2 c=128 or a=128 c=2
Since, a>c , a=128 and c=2 ie (128,2)