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telo118 [61]
3 years ago
7

Casey bought 3 books and an 7 CD's and paid $79. Her friend Jane bought a 5 books and 2

Mathematics
1 answer:
I am Lyosha [343]3 years ago
7 0

Answer:

  • book $3
  • CD $10

Step-by-step explanation:

We can let b and c represent the cost of a book and the cost of a CD, respectively. Then the purchases can be described by ...

  3b +7c = 79

  5b +2c = 35

Using Cramer's rule to find the solution, we have ...

  b = (7(35)-2(79))/(7(5) -2(3)) = 87/29 = 3

  c = (79(5)-35(3))/29 = 290/29 = 10

The cost of each book was $3; the cost of each CD was $10.

_____

Cramer's rule tells you the solution to ...

  ax +by = c

  dx +ey = g

is ...

  x = (bg -ec)/(bd -ea)

  y = (cd -ga)/(bd -ea) . . . . same denominator

This solution is fully equivalent to using elimination or substitution to solve the problem. Using these formulas effectively "cuts to the chase" without all the intermediate steps. The cross-multiplying pattern of differences is not hard to memorize.

You might be interested in
Story Problems
Gnom [1K]
Problem 3: Let x = price of bag of pretzels Let y = price of box of granola bars  
We have Lesley's purchase: 4x+2y=13.50
 And Landon's: 1x+5y=17.55 
 We can use the elimination method. Let's negate Landon's purchase by multiplying by -1. -1x-5y=-17.55 
 We add this four times to Lesley's purchase to eliminate the x variable.
 2y-20y=13.50-70.2
 -18y=-56.7
 y = $3.15 = Price of box of granola bars
 
 Plug back into Landon's purchase to solve for pretzels.
 x+5*3.15=17.55
 x+15.75=17.55
 x = $1.80 = price of bag of pretzels
  
 Problem 4.
 Let w = number of wood bats sold
 Let m = number of metal bats sold
 
 From sales information we have: w + m = 23
 24w+30m=606 
 Substitution works well here. Solve for w in the first equation, w = 23 - m, and plug this into the second. 
 24*(23-m)+30m=606
 552-24m+30m=606
 6m=54
 m=9 = number of metal bats sold
 Therefore since w = 23-m, w = 23-9 = 14. 14 wooden bats were sold.


6 0
3 years ago
Read 2 more answers
Help please which expression could NOT be used to find the quotiend of 1,377 and 9
topjm [15]

Answer:

C

Step-by-step explanation:


7 0
3 years ago
The probability distribution for the number of goals the Lions soccer team makes per game is given below. Number of Goals Probab
steposvetlana [31]

Answer: d. 0.55

Step-by-step explanation:

The given probability distribution:

Number of Goals     0            1            2          3           4

Probability             .05           .15        .35       .30           .15

The probability that in a given game the Lions will score less than 3 goals

= probability that in a given game the Lions will score less than or equal to 2

= 0.5+0.15+0.35

= 0.55

Hence, the correct option is d. 0.55

3 0
3 years ago
Which is an outlier out of 45,47,71,50,49 and 52
Elis [28]

The outlier is 71.

An outlier in a set of data is the one that is significantly lower or higher than the average of the totals. Whichever number skews the average is the outlier.

In this case, it's 71.

:)

6 0
4 years ago
In 1999 Daniel was 146 cm tall. He grew to be 176 cm by the year 2006. What was Daniel's rate of growth over this period of his
andreyandreev [35.5K]

Answer:

he grows by 5 cm every year between 1999 and 2006

Step-by-step explanation:

This is a arithmetic progression problem with the formula;

T_n = a + (n - 1)d

We are told that In 1999 Daniel was 146 cm tall. He grew to be 176 cm by the year 2006.

Thus;

a = 146

d = 2006 - 1999 = 7

Thus;

176 = 146 + (7 - 1)d

176 - 146 = 6d

30 = 6d

d = 30/6

d = 5 cm

Thus, he grows by 5 cm every year between 1999 and 2006

3 0
3 years ago
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