Answer: Choice A
Note: the range should be
. See explanation below.
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We can plug in any real number for x to get some output for y. The domain is the set of all real numbers in which we say
which is interval notation. It represents the interval from negative infinity to positive infinity.
The range is the set of possible outputs. The smallest output possible is y = -5 which occurs at the vertex (3,-5). We can get this y value or larger. So we can describe the range as the set of y values such that
and that translates to the interval notation
.
The square bracket says "include this endpoint" while the curved parenthesis says to exclude the endpoint. Your teacher mistakenly wrote
for choice A, when they should have written 
I think either your teacher made a typo or somehow the formatting messed up. Either way, choice A is the closest to the answer.
Answer: 100 miles
Step-by-step explanation:
300+3x=500+1x
subtract 1 from both sides
300+2x=500
subtract 300 from both sides
2x=200
divide 2
x=100
Step-by-step explanation:

So what you want to do for all of these is move the variable that you want to be the subject to one side of the equation and the other ones to the other side, then divide.
For example:
With number 1, m = 3n + 2p, since you want to make p the subject, first single out p by subtracting 3n from both sides.
m - 3n= 3n + 2p - 3n
2p = m - 3n
Then divide everything by 2.
2p / 2 = m/2 - 3n/2
p = , you could also say 1/2m - 3/2n
p = 1/2m - 3/2n
Next question: just do the same thing.
a = 3c - 4
a + 4 = 3c - 4 + 4
3c = a + 4
/3 /3 /3
c = 1/3a + 4/3
Next question: same process.
P - 2a = 2a - 2a + 2b
2b = P - 2a
/2 /2 /2
b = 1/2P - a