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3 years ago

15

Jan's average score after fifteen tests was 82. Her average on the next five tests was 90. What was her average score for all tw

enty tests?

1 answer:

Leokris [45]3 years ago

4 0

Answer:

86

Step-by-step explanation:

82+90=172

172/2 (divided by two because thats how many numbers we added up to get 172)

172/2=86

86 is your answer

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A number increased by 7 is 2 less than twice the number

Vedmedyk [2.9K]

n + 7 = 2n - 2

Add 2 to both sides:

n + 9 = 2n

Isolate n:

n = 9

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3 years ago

A cyclist travels 56 miles in 4 hours. What is the cyclist speed in feet per second

Step2247 [10]

Answer:

21.09 ft/s

Step-by-step explanation:

The first step is to create the ratio of speed/time.

$\frac{56 miles}{4 hours}$

Next we must simplify

$\frac{14 miles}{1 hour}$

Next we must convert 14 miles in to feet. There are 5280 feet in a mile.

14 * 5280ft = <u>75,920 feet</u>

Now for hours into seconds.

1 hour = 60 min, 60 min = 3600 seconds

Our new ratio is \frac{75920ft}{3600sec}

simplify.

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3 years ago

25 (a square) - 4 (b square) + 28bc - 49 (c square)

LUCKY_DIMON [66]

Answer:

(5a - [2b - 7c]) and (5a + [2b + 7c])

Step-by-step explanation:

Factor 25a^2 - 4b^2 + 28bc - 49c^2.

Note that - 4b^2 + 28bc - 49c^2 involves the variables b and c, whereas 25a^2 has only one variable. Thus, try to rewrite - 4b^2 + 28bc - 49c^2 as the square of a binomial:

- 4b^2 + 28bc - 49c^2 = -(4b^2 - 28bc + 49c^2), or

-(2b - 7c)^2.

Thus, the original 25a^2 - 4b^2 + 28bc - 49c^2 looks like:

[5a]^2 - [2b - 7c]^2

Recall that a^2 - b^2 is a special product, the product of (a + b) and (a - b). Applying this pattern to the problem at hand, we conclude:

Thus, [5a]^2 - [2b - 7c]^2 has the factors (5a - [2b - 7c]) and (5a + [2b + 7c])

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