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enot [183]
2 years ago
10

Sandra took 4 tests in math and her mean score was 18. I she scored 18, 22, and

Mathematics
1 answer:
Salsk061 [2.6K]2 years ago
7 0

Answer:

15

Step-by-step explanation:

(18+22+17+x)/4=18

18+22+17+x=18×4

57+x=72

x=72-57

x=15

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Write a system of equations to describe the situation below, solve using elimination.
Sedbober [7]

Answer:

The cost of hardbook is $9 and cost of paperback is $5.

Step-by-step explanation:

Let x be the price for hardback book and y be the price for paperback book.

Mr. Yamamoto purchased 42 new hardcover books and 64 new paperback books, which cost a total of $698.

We can write the equation as:

42x + 64y = 698

He also purchased 42 new hardcover books and 58 new paperback books, which cost a total of $668.

We can write the equation as:

42x + 58y = 668

We have to use the elimination method to solve the two equations.

We eliminate x by subtracting the two equations.

42x + 64y-(42x + 58y) = 698 - 668\\\Rightarrow 6y = 30\\\Rightarrow y = 5\\42x + 64(5) = 698\\\\\Rightarrow x = \displaystyle\frac{698 - 64(5)}{42}\\\\\Rightarrow x = 9

Thus, the cost of hardbook is $9 and cost of paperback is $5.

8 0
2 years ago
If x+y=10 and x-y=6 what is this value of x cube - y cube​
Jlenok [28]

Answer:

x cubed minus y cubed is equal to 504

Step-by-step explanation:

First we need to know what the values of x and y are.  We can do this pretty easily, by just solving both equations for x, and equating them to each other:

With the first:

x + y = 10

x = 10 - y

And with the other

x - y = 6

x = 6 + y

Now that we have two definitions of x, we can say that the expressions are equal, and solve for y:

10 - y = 6 + y

10 - 6 = y + y

4 = 2y

y = 2

And now that we know what y is, we can find x:

x = 10 - y

x = 10 - 2

x = 8

So x is equal to eight.  We can check our answer by plugging x into the other equation and seeing if we get the same value for y:

x - y = 6

8 - y = 6

-y = 6 - 8

-y = -2

y = 2

So we know we solved that correctly.

Now if we cube each number, eight cubed is equal to 512, and 2 cubed is equal to 8.  If we subtract the latter from the former we get 504.

so x cubed minus y cubed is equal to 504

7 0
3 years ago
Describe how to determine if a number is a solution to an equation.
marin [14]

Step-by-step explanation:

Determine whether a number is a solution to an equation.

Substitute the number for the variable in the equation.

Simplify the expressions on both sides of the equation.

Determine whether the resulting equation is true. If it is true, the number is a solution. If it is not true, the number is not a solution.

Hoped that helped:P

5 0
2 years ago
Read 2 more answers
Please help on 10 and 11
balu736 [363]
The first one is independent, and the second one is dependent.
4 0
3 years ago
7c-11=17 what does c equal. Plz show work. Thanks :D
Gnom [1K]
Since you are subtracting 11 on the side with the variable, you have to add it on the other side. 17+11=28. Then, to solve the problem you are left with, 7c=28. You are multiplying on the side of the variable, so you divide 28 by 7. Your answer to the problem is C=4 i hope this helps
4 0
3 years ago
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