Answer: Choice C) -11
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Explanation:
The first equation given is y = 3 - 1/2x
In other words, y is the same as 3 - 1/2x.
We can replace y in the second equation with 3 - 1/2x
This is known as substitution (think of a substitute teacher who is a temporary replacement for your teacher)
Doing this leads to...
3x+4y = 1
3x+4*y = 1
3x+4*( y ) = 1
3x+4*( 3 - 1/2x ) = 1 <<--- y has been replaced with 3-1/2x
3x+4*(3) +4*(-1/2x) = 1
3x+12-2x = 1
3x-2x+12 = 1
x+12 = 1
x+12-12 = 1-12 <<-- subtracting 12 from both sides
x = -11
Which is why the answer is choice C) -11
Answer:
a) 91 1/6 gallons
b) 2502 miles
Step-by-step explanation:
You are given a number of miles and a number of gallons for the car. The ratio of these numbers is ...
(261 mi)/(14.5 gal) = 18 mi/gal
We presume this value is constant for this car. Then the questions can be answered by forming and solving a proportion:
a) 1641 miles/(gallons) = 18 mi/(1 gal)
Multiplying by gallons and dividing by 18 mi/gal, we get
1641/18 gal = (gallons) = 91 1/6 gal
It will take 91 1/6 gallons of gasoline for Mary to drive to her friend's house.
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b) Same deal, but the miles are unknown.
(miles)/(139 gal) = (18 mi)/(1 gal)
Multiplying by 139 gal gives ...
(18 mi)·139 = (miles) = 2502 mi
139 gallons of gasoline will let Mary drive 2502 miles.
Imagine what x is quantity of stools. So
3x+120=4x
x=120
120 stools in cafeteria
120 chairs in cafeteria
120+120=240
There 240 people can sit in this cafeteria
The partial products are: 42 x 28 = (40 + 2) x (20 + 8) = 40 x 20 + 40 x 8 + 2 x 20 + 2 x 8
= 800 + 320 + 40 + 16 Hope this helped.
