Answer: the system of equations that represents this situation are
12x + 6y = 180
x = 2y
Step-by-step explanation:
Let x represent the number of hardcover books that were sold in a day.
Let y represent the number of paperback books that were sold in a day.
The discount bookstore sells hardcover books for $12 and paperback books for $6. The total sales that day were $180. It means that
12x + 6y = 180
The number of hardcover books sold that day was twice the number of paperback books. It means that
x = 2y
Answer:
The value is 
Step-by-step explanation:
From the question we are told that
The area of the rectangular pen is 
The cost of material used to make one side is 
The cost of material used to make the other sides is 
Now , the fence to be build around the rectangular pen has four sides, the first opposite sides are equal, let assume each of the to be x yard and the other opposite sides are also equal as well let assume of the to be y yard
So the cost is mathematically represented as

=> 
=> 
Now the area of the fence is mathematically represented as

=> 
=> ![C = 9x + 6[\frac{24}{x} ]](https://tex.z-dn.net/?f=C%20%3D%20%20%209x%20%20%2B%20%206%5B%5Cfrac%7B24%7D%7Bx%7D%20%5D)
=> ![C = 9x + [\frac{144}{x} ]](https://tex.z-dn.net/?f=C%20%3D%20%20%209x%20%20%2B%20%20%5B%5Cfrac%7B144%7D%7Bx%7D%20%5D)
Now differentiating


At minimum 
So




Now substituting for x in the equation above to obtain minimum cost
![C = 9(5.66) + [\frac{144}{5.66} ]](https://tex.z-dn.net/?f=C%20%3D%20%20%209%285.66%29%20%20%2B%20%20%5B%5Cfrac%7B144%7D%7B5.66%7D%20%5D)

Solve like an equation,
You need x by itself.
Since x is on the denominator, multiply both sides by x to clear the fraction.
Tan 12 = 10/x
x Tan12 = 10
Divide both sides by Tan12
x = 10/(Tan12)
x = 47
There is no whole number that is half of 11 but the half number is 5.5
2d + 14 ( "d" is the number of days after today, and "14" comes from how many feet deep the water is today)