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3 years ago

Solve the system for x and y -3x+8y=103 -5x-8y=-255

Mathematics

1 answer:

Romashka-Z-Leto [24]3 years ago

3 0

9514 1404 393

Answer:

(x, y) = (19, 20)

Step-by-step explanation:

The coefficients of y are opposites, so we can add the two equations to eliminate y.

(-3x +8y) +(-5x -8y) = (103) +(-255)

-8x = -152

x = 19 . . . . . . . divide by -8

Substituting into the first equation, we have ...

-3(19) +8y = 103

8y = 160

y = 20

The solution is (x, y) = (19, 20).

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A chef is going to use a mixture of two brands of Italian dressing. The first brand contains 8% vinegar, and the second brand co

jok3333 [9.3K]

Answer:

76 mL of 8% and 304 mL of 13%

Step-by-step explanation:

Set up a table like this (this is the same table for any mixture problem):

mL total * % vinegar = % vinegar/mL

13%

total %

What you do with this table is multiply the first 2 columns and they equal the last column. We already know the middle column's entries from what we are given. But remember that a percent needs to be expressed as a decimal:

mL total * % vinegar = % vinegar/mL

8% .08

13% .13

total %

Now we also know that the total he wants to make is 380 mL that is 12%, so all that info goes into the last row:

mL total * % vinegar = % vinegar/mL

8% .08

13% .13

total % 380 .12

If he wants this total mixture to come from the 8% and the 13% vinegars, he is mixing them together, or adding them. We need to know how much 8% + how much 13% will give us 380 mL of 12%. So we can fill in the amounts accordingly. If he has x mL of 8%, then he will have 380 - x of 13%. The table tells us that we are multiplying the first 2 columns to get the third, so we will do that at the same time:

mL total * % vinegar = % vinegar/mL

8% x * .08 = .08x

13% 380 - x * .13 = .13(380 - x)

total % 380 * .12 = 45.6

Since we are adding the different vinegars together to get the total, we can do that with the last column as well. This is our equation:

.08x + .13(380 - x) = 45.6 Multiply everything through by 100 to get rid of the decimals now:

8x + 13(380 - x) = 4560 and

8x + 4940 - 13x = 4560 and

-5x = -380 so

x = 76

This means that there is 76 mL of 8% and 380 - 76 = 304 mL of 13%

8 0

3 years ago

please solve all of them Elaine bought a total of 15 shirts and pairs of pants She bought 7 more shirts then pants how many of e

mihalych1998 [28]

Answer

Question 1

4 pants

11 shirts

Question 2

Shady has 30 video games.

Preston has 19 video games.

Question 3

1 muffin costs $1.5

1 quart of milk costs $3

Explanation

Question 1

Let the number of shirts be s

Let the number of pants be p

She bought a total of 15 shirts and shirts

s + p = 15

She bought 7 more shirts than pants.

s = 7 + p

So, we can solve the simultaneous equation.

s + p = 15

s = 7 + p

Substitute for s in equation 1

s + p = 15

7 + p + p = 15

7 + 2p = 15

2p = 15 - 7

2p = 8

Divide both sides by 2

(2p/2) = (8/2)

p = 4 pants

s = 7 + p = 7 + 4 = 11 shirts

Question 2

Let the number of games Shady has be s

Let the number of games Preston has be p

Together, they have a total of 49 video games

s + p = 49

Shady has 11 more games than Preston.

s = 11 + p

So, we can solve the simultaneous equation.

s + p = 49

s = 11 + p

Substitute for s in equation 1

s + p = 49

11 + p + p = 49

11 + 2p = 49

2p = 49 - 11

2p = 38

Divide both sides by 2

(2p/2) = (38/2)

p = 19 video games

s = 11 + p = 11 + 19 = 30 video games

Question 3

Let the cost of a muffin be m

Let the cost of a quart of milk be q

The cost of 8 muffins and 2 quarts of milk is $18.

8m + 2q = 18

The cost of 3 muffins and 1 quart of milk is $7.50

3m + q = 7.5

So, we can solve the simultaneous equation

8m + 2q = 18

3m + q = 7.5

Solving this,

m = 1.5 dollars

q = 3 dollars

Hope this Helps!!!

3 0

1 year ago

Need help immediately

vekshin1

The answer is 6*square rooted*2

3 0

3 years ago

Find the value of this expression if X = -1 and Y = -5 xy over -6

Thepotemich [5.8K]

$\frac{xy}{-6} = \frac{(-1)(-5)}{-6} = \frac{5}{-6} = -\frac{5}{6}$

4 0

3 years ago

I need help me with number 7

Lina20 [59]

-7=-9+n/8
Add 9 to both sides
2=n/8
Multiply 8 on both sides
Final Answer: 16=n

4 0

4 years ago