Made this question as soon as possible

The hardcover version of a book weighs 7 ounces while its paperback version weighs 5 ounces. Forty-five copies of the book weigh

konstantin123 [22]

Answer:

33 copies were paperback and 12 were hardcover.

Step-by-step explanation:

Let h represent the number of hardcover copies and p represent the number of paperback copies.

We know that the total number of copies was 45; this gives us the equation

h+p = 45

We know that each hardcover copy is 7 ounces; this gives us the expression 7h.

We also know that each paperback copy is 5 ounces; this gives us the expression 5p.

We know that the total weight was 249 ounces; this gives us the equation

7h+5p = 249

Together we have the system

$\left \{ {{h+p=45} \atop {7h+5p=249}} \right.$

We will use elimination to solve this. First we will make the coefficients of the variable p the same; to do this, we will multiply the top equation by 5:

$\left \{ {{5(h+p=45)} \atop {7h+5p=249}} \right. \\\\\left \{ {{5h+5p=225} \atop {7h+5p=249}} \right.$

To eliminate p, we will subtract the equations:

$\left \{ {{5h+5p=225} \atop {-(7h+5p=249)}} \right. \\\\-2h=-24$

Divide both sides by -2:

-2h/-2 = -24/-2

h = 12

There were 12 hardcover copies sold.

Substitute this into our first equation:

12+p=45

Subtract 12 from each side:

12+p-12 = 45-12

p = 33

There were 33 paperback copies sold.

3 0

4 years ago

Read 2 more answers

If you are driving 20 meters per second, what would be the equivalent of that in miles per hour?

melomori [17]

$\frac{20 meters}{1 second} \frac{60 seconds}{1 minute} \frac{60 minutes}{1 hour}$

the fractions are set up so that each unit cancels out until its only meters/hour

you can multiply all the numerators together to get 72000 and all the denominators to get 1

72000 meters/1 hour

72000 meters in 1 hour

hope this helped

8 0

3 years ago

Help me please. <br>Help me please. <br>Help me please.

Gnesinka [82]

A)
To be similar triangles have to have equal angles
triangle ZDB'
1)angle Z=90 degrees
triangle B'CQ
1) angle C 90 degrees

angle A'B'Q=90
DB'Z+A'B'Q+CB'Q=180, straight angle
DB'Z+90+CB'Q=180
DB'Z+CB'Q=90

triangle ZDB'
DZB'+DB'Z=180-90=90

DB'Z+CB'Q=90
DZB'+DB'Z=90
DB'Z+CB'Q=DZB'+DB'Z
2)CB'Q=DZB' (these angles from two triangles ZDB' and B'CQ )
3)so,angles DB'Z and B'QC are going to be equal because of sum of three angles in triangles =180 degrees and 2 angles already equal.
so this triangles are similar by tree angles
b)
B'C:B'D=3:4
B'D:DZ=3:2
CQ-?
DC=AB=21
DC=B'C+B'D (3+4= 7 parts)
21/7=3
B'C=3*3=9
B'D=3*4=12
B'D:DZ=3:2
12:DZ=3:2
DZ=12*2/3=8
B'D:DZ=CQ:B'C
3:2=CQ:9
CQ=3*9/2=27/2

c)
BC=BQ+QC=B'Q+QC
BQ' can be found by pythagorean theorem

3 0

3 years ago

In the last election 60% of the class members voted if the class has 120 members how many members voted in the last election

IgorLugansk [536]

Answer:

72 students

Step-by-step explanation:

1. change 60% to decimal= 0.6

2. multiply 0.6 by 120

3. 72

6 0

4 years ago

Perry connects a blue garden hose and a green garden hose to make one long hose. The blue hose is 10.5 feet. The green hose is 1

swat32

Answer:

22.25 ft long

if you add 10.5 with 11.75 you'll get 22.25

7 0

3 years ago

Made this question as soon as possible ​

Made this question as soon as possible