Answer:
$36
Step-by-step explanation:
we need to find the cost of 12 items, and the function of determining the cost is C(x)=2x+12, where x is the number of items (the input value of the function)
we know that there are 12 items, so in this function, x=12
substitute x as 12 in the function; the x in C(x) also gets substituted as 12, as 12 is the input value and the value of C(x) is the output
C(12)=2(12)+12
multiply
C(12)=24+12
add
C(12)=36
that means, for 12 items, the cost will be $36
Answer:

Step-by-step explanation:
This is just a perfect square
Slope = (2+4)/(1-4) = 6/-3 = -2
passing thru (1.2)
y = mx + b
b = y - mx
b = 2 - (-2)(1)
b = 2 + 2
b = 4
equation
y = -2x + 4
Answer:
5x -7y = 21
Step-by-step explanation:
A sketch can convince you that BC is a transversal perpendicular to parallel lines AB and CD. The question asks for an equation for CD, so we just need to write the equation of a line through D that is parallel to AB.
One way to do this is to equate the slopes of the parallel lines:
∆y/∆x for AB = ∆y/∆x for CD
(y2 -y1)/(x2 -x1) = (y -2)/(x -7) . . . . . . where (x1, y1) = A; (x2, y2) = B; (7, 2) = D
(4 -(-1))/(1 -(-6)) = (y -2)/(x -7)
5(x -7) = 7(y -2) . . . . . . . . . . . . . cross multiply
5x -7y = 21 . . . . . . . . . . . . . . . . add 35 -7y, simplify
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Note that the graph shows the line CD is named "b", and its equation is shown at upper left. Multiplying that equation by -1 gives the one shown here.