Answer:
<h3><em>
D. 880 = 45d + 70; 18 days.</em></h3>
Step-by-step explanation:
We are given fixed monthly charge = $70.
The cost of preschool per day = $45.
Number of days = d.
Total cost of d days = cost per day × number of days + fixed monthly charge.
Therefore, we get equation
880 = 45×d+70
<h3>880 = 45d +70.</h3>
Now, we need to solve the equation for d.
Subtracting 70 from both sides, we get
880-70 = 45d +70-70
810=45d
Dividing both sides by 45, we get

18=d.
Therefore,<em> 18 days Barry attended preschool last month.</em>
<em>Therefore, correct option is D option.</em>
<h3><em>
D. 880 = 45d + 70; 18 days.</em></h3>
Information we know:
a 15 ounce cup takes 3 second to fill
determine variables:
x=3
y=15
rate:
y/x=3/15= 0.2
fixture an equation:
y=kx
y=0.2x
plug in 40 for x:
y=0.2(40)
=8
Thus, it should take 8 seconds to fill a 40-ounce cup of soda.
(c)
We notice that they already have common denominators, therefore we can just add the numerators up.
(x+y+x-y)/2xy=
2x/2xy
Dividing both top and bottom by 2x, we get
<h2><u><em>
1/y</em></u></h2>
-Hunter