I think the number is 30. Hope this works. Good luck!
Given
The demand function

To determine:
a) The revenue function.
b) The marginal revenue.
c) The marginal revenue when x=200.
d) The equation of tangent, and its derivation.
Explanation:
It is given that,

a) The revenue function is given by,

b) The marginal revenue function is,

c) The marginal revenue when x=200 is,

Hence, the marginal revenue is 3.84.
d) Let y=mx+c is the tangent.
Then,

That implies, for y=12.68, and x=200,

Hence, the equation of tangent is,
Answer:
x= -8 x=2
Step-by-step explanation:
x^2 +6x-6= 10
Subtract 10 from each side
x^2 +6x-6-10= 10-10
x^2 +6x-16 = 0
What 2 number multiply to -16 and add to 6
8 * -2 = -16
8 -2 = 6
(x+8) (x-2)=0
Using the zero product property
x+8=0 x-2=0
x= -8 x=2
Subtract 10 from both sides :
-3y + 10 - 10 = -14 -10
3y = -24
divide both sides with 3 :
y = -8