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telo118 [61]
4 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]4 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.

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the Royal fruit company produces two types of fruit drinks. the first type is 20% pure juice,the second type is 100% pure fruit
skad [1K]

30 pints of first type and 130 pints of second type drinks must be used to make the mixture.

<em><u>Explanation</u></em>

Lets assume, the amount of first type drink is x pints.

As the total amount of the mixture is 160 pints, so the amount of second type drink = (160-x) pints.

The first type is 20% pure juice, the second type is 100% pure fruit juice and the mixture is 85% pure fruit juice. So the equation will be .....

0.20x+1.00(160-x)= 0.85*160\\ \\ 0.20x+160-x=136\\ \\ -0.80x= -24\\ \\ x=\frac{-24}{-0.80}=30

So, the amount of first type drink is 30 pints and the amount of second type drink is (160-30)pints =130 pints.

5 0
3 years ago
How many numbers between 25 and 400 are divisible by 11? find their sum
kicyunya [14]

Answer:

14, 21, 28, and 196

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6 0
3 years ago
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inna [77]
What kind of question is this lol ? i don’t even understand it
7 0
3 years ago
Given f(x) = 10 -2xfind f(7). –4 3 7 56
strojnjashka [21]

Answer: f(7)=-4

Step-by-step explanation:

1. You have the following function given in  the problem:

f(x)=10-2x

2. Then, to find f(7) asked in the exercise, you only need to substitute x=7 (which is the input value) into the given function.

3. Therefore, keeping the above on mind, you obtain that f(7) is:

x=7

f(7)=10-2(7)

f(7)=10-14

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3 0
3 years ago
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3 years ago
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