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3 years ago

All perfect numbers from 20 to 30

Mathematics

1 answer:

lana [24]3 years ago

7 0

Answer:

There is only one perfect number between 20 to 30 which is 28.

<h3>Explanation:</h3>

The number 28 is a perfect number because its factors are 1, 2, 4, 7, 14 and 28.

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Masja [62]

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3 years ago

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A recipe calls for 10 cups of oatmeal. Benjamin wants to make 1/5 fewer servings than the recipe makes.

miskamm [114]

The answer is c: .2 cups of oatmeal

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4 years ago

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Nancy bought a soft drink for 2 dollars and 9 candy bars. She spent a total of 38 dollars. How much did each

natima [27]

Answer:

Step-by-step explanation:

Because we know that Nancy bought a drink for 2 dollars, and we are just trying to find the cost of the candy bars, we can subtract 2 dollars from the drink from the total cost:

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3 years ago

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Lindsay is 5 years younger than Mark. Seven years ago, the sum of their ages was 31.

Rashid [163]

Answer:

The present age of Mark is 25 years.

And present age of Lindsay is 20 years.

Step-by-step explanation:

Let us assume:

The present age of Lindsay = l

The present age of Mark = m

⇒ Age of Lindsay seven years ago = (l -7) years

and Age of Mark seven years ago = (m -7) years

According to question:

Lindsay is 5 years younger than Mark ⇒ l = m - 5

Seven years ago, the sum of their ages was 31 ⇒ (l-7) + (m -7) = 31

So, the given set of equation are:

l = m - 5 ......... (1)

(l-7) + (m -7) = 31

⇒ ((m - 5) -7) + (m -7) = 32 (from (1)

or, m -12 + m - 7 = 31

or, 2m = 31 + 19 = 50

⇒ m = 50 / 2 = 25, or m = 25

Hence,the present age of Mark = 25 years

So,the present age of Lindsay = 25 - 5 = 20 years

7 0

3 years ago

Add the equations. What value belongs in the green box? 3x + 2y = 9 -x - 2y = 4 [?] + [?] = [?] A. 4x B. 2x C. -3x D. -2x

Naddika [18.5K]

Consider the first blank is the green box.

Given:

The equations are

$3x+2y=9$

$-x-2y=4$

To find:

The value belongs in the green box

Solution:

We have,

$3x+2y=9$ ...(i)

$-x-2y=4$ ...(ii)

Adding (i) and (ii), we get

$3x+2y-x-2y=9+4$

$(3x-x)+(2y-2y)=13$

$2x+0=13$

So, the value for the first black is 2x. It means the value belongs in the green box is 2x.

The values of three blanks are 2x, 0 and 13 respectively.

Therefore, the correct option is B.

6 0

3 years ago