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3241004551 [841]
3 years ago
5

A particular chemistry book costs $6 less than a particular physics book, while two such chemistry books and three such physics

books cost a total of $123. Construct two simultaneous equations and solve them using the substitution method.
Mathematics
1 answer:
sladkih [1.3K]3 years ago
3 0

Answer:

Step-by-step explanation:

Let's say the Physics book costs $x

The Chemistry book will cost $x - $6

Two such Chemistry books will cost;

2($x - $6) = $(2x - 12)

Three such Physics books cost $3x

$(2x - 12) + $3x = $123

$5x - $12 = $123

$5x = $111

x = $22\frac{1}{5}

So the Physics book costs;  $22\frac{1}{5}

and the Chemistry book costs  $22\frac{1}{5} - 6 =  $16\frac{1}{5}

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How do I solve this equation
Anestetic [448]
-x - y = 8
2x - y = -1

Ok, we are going to solve this in 2 parts.  First we have to solve for one of the variables in one of the equation in terms of the other variable.  I like to take the easiest equation first and try to avoid fractions, so let's use the first equation and solve for x.

-x - y = 8      add y to each side
-x = 8 + y      divide by -1
x = -8 - y

So now we have a value for x in terms of y that we can use to substitute into the other equation.  In the other equation we are going to put -8 - y in place of the x.

2x - y = -1
2(-8 - y) - y = -1      multiply the 2 through the parentheses
-16 - 2y - y = -1      combine like terms
-16 - 3y = -1            add 16 to both sides
-3y = 15                   divide each side by -3
y = -5

Now we have a value for y.  We need to plug it into either of the original equations then solve for x.  I usually choose the most simple equation.

-x - y = 8
-x - (-5) = 8            multiply -1 through the parentheses
-x + 5 = 8                subtract 5 from each side
-x = 3                      divide each side by -1
x = -3

So our solution set is

(-3, -5)

That is the point on the grid where the 2 equations are equal, so that is the place where they intersect.

4 0
3 years ago
Find the lateral area of the figure geometry
Arlecino [84]

Answer:

  • A) 420 in²

Step-by-step explanation:

The lateral surface area excludes the area of top and bottom faces.

Given is the right pentagonal prism with side length of 7 in and height of 12 in.

<u>The lateral area is:</u>

  • L = Ph = 5*7*12 = 420 in²

Correct choice is A

6 0
3 years ago
Please help I am desperate
Phoenix [80]

Answer:

see below

Step-by-step explanation:

72pi cubic inches

1/3 pi r ^2 * h = 72 pi

1/3 r^2 h = 72

You can theoretically find infinite answers to this and get enough points for the semester where you don't have to do work anymore. I will list a couple more possible answers below

r = radius, h = height

r = 2, h = 54

r = 3, h = 24

r = 4, h = 27/2

r = √(1/pi), h = 72pi

5 0
3 years ago
A two year college degree that focus on natural science, engineering, and mathematics is called
nikklg [1K]

Answer:

Its going to be associate of science.

Step-by-step explanation:

3 0
3 years ago
Read 2 more answers
there is a loss of 20% by selling a photocopy machine for rs 60000 at what price will the machine be sold to gain 12% find it
notsponge [240]

Answer:

Step-by-step explanation:

Loss is 20%

S.P=Rs60000

C.P=S.P*100/100-loss%

=60000*100/80=Rs75000

So he brought is at Rs75000

Now he wants 12% profit

So

S.P=(100+profit%)/100*C.P

=100+12/100*75000

=112/100*75000=Rs 84000

He will have to sell Rs14000 more to gain profit of 12%

6 0
4 years ago
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