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3 years ago

Select the correct solution for the expression. 2/5 + 3/8

Mathematics

1 answer:

yaroslaw [1]3 years ago

6 0

Answer:

because when you try to find the common denominator the lowest number is 40. so you then multiply the 2x8 and the 3x5 that gives you 16/40 + 15/40 = 31/40

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Brass is made from a mixture of copper and other elements. a mixture that is 80% copper is combined with a mixture that is 60% c

algol [13]

The equation that can be used to find x, the amount of the 60% mixture used to create the 65% mixture is:

0.60*x + 0.80*(100 - x) = 0.65*(100).

<h3>Which equation we should use?</h3>

First, let's define two variables:

x = pounds of the 60% copper brass.
y = pounds of the 80% copper brass.

We know that we want to make 100 lb of 65% copper brass, then we must have that:

x + y = 100

And the percentage of copper before and after mixing must be the same, so we can write:

0.60*x + 0.80*y = 0.65*(x + y).

(where the percentages are written in decimal form).

Then we have a system of equations:

x + y = 100

0.60*x + 0.80*y = 0.65*(x + y).

To get a single equation, we can isolate the variable "y" on the first equation:

y = 100 - x

Now we replace that in the other equation:

0.60*x + 0.80*(100 - x) = 0.65*(100).

This is what we wanted to get, an equation that can be used to find x, the amount of the 60% mixture used to create the 65% mixture.

If you want to learn more about systems of equations:

brainly.com/question/13729904

#SPJ1

4 0

2 years ago

Two friends sold many pieces of furniture and made $1550 during their garage sale. They had fifteen more $10 bills than $50 b

Novosadov [1.4K]

Answer:

The number of $ 10 bills is 37, the number of $ 20 is 6 and the number of $ 50 bills is 22.

Step-by-step explanation:

Let n₁ = number of $ 10 bills,

Let n₂ = number of $ 20 bills and

Let n₃ = number of $ 50 bills

Given that 10n₁ + 20n₂ + 50n₃ = 1550 (1)

Also, since we have fifteen more $10 bills than $50 bills, n₁ = n₃ + 15 (2)

and we have 4 more than three times as many $20 bills as $50 bills. n₃ = 3n₂ + 4. (3)

substituting equations (2) and (3) into (1), we have

10(n₃ + 15) + 20n₂ + 50n₃ = 1550

expanding the bracket, we have

10n₃ + 150 + 20n₂ + 50n₃ = 1550

collecting like terms, we have

60n₃ + 150 + 20n₂ = 1550

inserting equation (3), we have

60(3n₂ + 4) + 150 + 20n₂ = 1550

expanding the bracket, we have

180n₂ + 240 + 150 + 20n₂ = 1550

collecting like terms, we have

200n₂ + 390 = 1550

subtracting 390 from both sides, we have

200n₂ = 1550 - 390

200n₂ = 1160

dividing both sides by 200, we have

n₂ = 1160/200

n₂ = 5.8

n₂ ≅ 6 since it cannot be a fraction.

Substituting this into (3), we have

n₃ = 3n₂ + 4 = 3(6) + 4 = 18 + 4 = 22

substituting n₃ into (2), we have

n₁ = n₃ + 15 = 22 + 15 = 37

So, the number of $ 10 bills is 37, the number of $ 20 is 6 and the number of $ 50 bills is 22.

3 0

3 years ago

Inverse of y=(x/2)^2

Lady bird [3.3K]

Tell me if the answer is true or wrong

6 0

3 years ago

Select the correct answer.<br>What is the solution of 3x + y = 9 and 3x - 5y = 15

KATRIN_1 [288]

The answer is x= 3.3 and the y=-., hope this helps out !

7 0

3 years ago

Mario has LaTeX: 2\frac{1}{4}2 1 4 pounds of trail mix. He puts equal amounts of the trail mix into 6 bags for a hike with his f

ioda

Answer:

<h2><em>0.375 pounds </em></h2>

Step-by-step explanation:

Let the amount of trail mix in each bag be x pounds. If Mario has $2\frac{1}{4}$ pounds of trail mix and puts equal amounts of the trail mix into 6 bags for a hike with his friends, the amount of trail mix in each bag can be derives using the expression;

$2\frac{1}{4} = 6 * x$

solving for x

$\dfrac{9}{4} = 6x\\\\2.25 = 6x\\\\divide\ both \ sides \ by \ 6\\\\\dfrac{2.25}{6} = \dfrac{6x}{6} \\\\x = 0.375\\$

<em>Hence 0.375 pounds of trail mix will be in each bag</em>

7 0

3 years ago