Answer:
90 engines must be made to minimize the unit cost.
Step-by-step explanation:
Vertex of a quadratic function:
Suppose we have a quadratic function in the following format:
It's vertex is the point 
In which
Where
If a>0, the minimum value of the function will happen for 
C(x)=x²-180x+20,482
This means that 
How many engines must be made to minimize the unit cost?
x value of the vertex. So
90 engines must be made to minimize the unit cost.
I suspect you meant
"How many numbers between 1 and 100 (inclusive) are divisible by 10 or 7?"
• Count the multiples of 10:
⌊100/10⌋ = ⌊10⌋ = 10
• Count the multiples of 7:
⌊100/7⌋ ≈ ⌊14.2857⌋ = 14
• Count the multiples of the LCM of 7 and 10. These numbers are coprime, so LCM(7, 10) = 7•10 = 70, and
⌊100/70⌋ ≈ ⌊1.42857⌋ = 1
(where ⌊<em>x</em>⌋ denotes the "floor" of <em>x</em>, meaning the largest integer that is smaller than <em>x</em>)
Then using the inclusion/exclusion principle, there are
10 + 14 - 1 = 23
numbers in the range 1-100 that are divisible by 10 or 7. In other words, add up the multiples of both 10 and 7, then subtract the common multiples, which are multiples of the LCM.
<span> For this case, the first thing that we must take into account is the following conversion:
</span>
<span> Thus, the relationship between gallons and pints is given by the following equation:
</span>
<span> Therefore, if we want to know how many pints a gallon is, we substitute g = 1, obtaining:
</span>
<span>
Answer:
The equation that relates the number of pints given the number of gallons is:
</span>
<span>
</span>
