If 18/6=3, then we divide 15/3=5, therefore, x=5
7. A
8. F
9. C
those are the answers on that page
We are given:
number of kilometers = 875.52 km
time = 38.4 hours
We need to calculate the unit rate, which means that we need to find the number of kilometers in one hour.
To do so, we will simply divide the total number of kilometers by the total time as follows:
unit rate = 875.52 / 38.4 = 22.8 km/hour
Whenever you face the problem that deals with maxima or minima you should keep in mind that minima/maxima of a function is always a point where it's derivative is equal to zero.
To solve your problem we first need to find an equation of net benefits. Net benefits are expressed as a difference between total benefits and total cost. We can denote this function with B(y).
B(y)=b-c
B(y)=100y-18y²
Now that we have a net benefits function we need find it's derivate with respect to y.

Now we must find at which point this function is equal to zero.
0=100-36y
36y=100
y=2.8
Now that we know at which point our function reaches maxima we just plug that number back into our equation for net benefits and we get our answer.
B(2.8)=100(2.8)-18(2.8)²=138.88≈139.
One thing that always helps is to have your function graphed. It will give you a good insight into how your function behaves and allow you to identify minima/maxima points.
Answer:
15 seconds
Step-by-step explanation:
120/8=15