PLEASE HELP

X + Y = 6
X + Y = 4

C. (5,1)

Step-by-step explanation:

Well first we need to single out y in the following equation,

x - y = 4

so,

-x to both sides -y = -x + 4

divide the - by everything y = x - 4.

Now that we have our two equations.

x + y = 6

y = x - 4

We can substitute the y in the x + y = 6 for x - 4

x + x - 4 = 6

2x - 4 = 6

Add the 4

2x = 10

Divide the 2

x = 5.

Now that we have the x we can plug it in for x in x + y = 6

5 + y = 6

-5 to both sides

y = 1

So the solution is (5,1)

For more proof look at the image below.

a. she will receive a refund of $278.

step-by-step explanation:

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204