28 is a multiple of 7 and also a factor of seven!
X + y = 23000
x.08 + y.09 = 2040
x = 23000 - y
(23000 - y) .08 + y.09 = 2040
1840 - .08y + .09y = 2040
Simplify
.01y = 200
Simplify
Y = 20000
X + 20000 = 23000
X = 3000
CHECK: .08x + .09(20000) = 2040
.08x + 1800 = 2040
Simply .08x = 240
X = 3000
Answer:
The water temperature that produces the maximum number of salmon swimming upstream is approximately 12.305 degrees Celsius.
Step-by-step explanation:
Let
, for
.
represents the temperature of the water, measured in degrees Celsius, and
is the number of salmon swimming upstream to spawn, dimensionless.
We compute the first and second derivatives of the function:
(Eq. 1)
(Eq. 2)
Then we equalize (Eq. 1) to zero and solve for
:

And all roots are found by Quadratic Formula:
, 
Only the first root is inside the given interval of the function. Hence, the correct answer is:

Now we evaluate the second derivative at given result. That is:


According to the Second Derivative Test, a negative value means that critical value leads to a maximum. In consequence, the water temperature that produces the maximum number of salmon swimming upstream is approximately 12.305 degrees Celsius.
Answer:
Conver the sales tax to a decimal and ad it to 1, then multiple that total to the price of the item. Please mark as breinlest