From the sketch, you can see that the distance from arbitrary point to x-axis is y.
The cost of manufacturing 
units is
, where 
cost per unit and 
fixed cost.
Given that
Subtract the second equation from the second,
The variable cost per unit is 
.
n, n + 2, n + 4 - three consecutive odd ntegers
n + (n + 2) + (n + 4) = 5(n + 2) - 18 |use distributive property
n + n + 2 + n + 4 = (5)(n) + (5)(2) - 18
3n + 6 = 5n + 10 - 18
3n + 6 = 5n - 8 |subtract 6 from both sides
3n = 5n - 14 |subtract 5n from both sides
-2n = -14 |divide both sides by (-2)
n = 7
n + 2 = 7 + 2 = 9
n + 4 = 7 + 4 = 11
Answer: 7, 9, 11.
