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Mathematics

1 answer:

Nikitich [7]3 years ago

4 0

Answer is D. 288 . i am glad to help

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We have two varieties of concrete that we can mix together. One is 5% water and 95% concrete mix, and the other is 20% water and

Orlov [11]

Answers:

20 pounds of the 95% concrete mix
10 pounds of the 80% concrete mix

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Explanation:

x = amount of the 95% concrete mix

y = amount of the 80% concrete mix

Type A mix has 95% concrete. If we have x pounds of this, then 0.95x pounds is pure concrete. Type B mix has 80% concrete. If there are y pounds of this, then 0.80y pounds is pure concrete.

So far we have 0.95x+0.80y pounds of pure concrete from the two mixes

Divide this over 30 to get (0.95x+0.80y)/30

Setting this equal to 0.90 means we want the final mix to be 90% concrete.

Since we want 30 pounds total, we can say x+y = 30 which solves to y = 30-x. We'll use this later

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(0.95x+0.80y)/30 = 0.90

0.95x+0.80y = 30*0.90 .... multiply both sides by 30

0.95x+0.80y = 27

0.95x+0.80(30-x) = 27 ..... plug in y = 30-x

0.95x+0.80*30-0.80*x = 27

0.95x+24-0.80x = 27

0.15x+24 = 27

0.15x = 27-24 ..... subtracting 24 from both sides

0.15x = 3

x = 3/0.15 ........... dividing both sides by 0.15

x = 20

y = 30-x

y = 30-20

y = 10

5 0

3 years ago

What is the solution of x + y = 2 and 2x + 5y = 16?

elena55 [62]

Multiply the first equation by two to get 2x + 2y = 4.
Subtract the second equation from the first equation to get -3y = -12

y = 4.

Plug y back in to get x = -2.

5 0

3 years ago

Read 2 more answers

-3, -2,-1, 0, 1, 2, 3, are called_______

loris [4]

Answer: Integers

Step-by-step explanation: To help introduce the set

of integers, let's use the number line shown below.

Notice that on a number line, 0 is in the middle, all numbers to the

left of 0 are negative, and all numbers to the right of 0 are positive.

The set of integers includes the set of whole numbers, {0, 1, 2, 3, ...},

which appear at 0 and to the right of 0 on the number line.