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2 years ago

BRAINLIESTT ASAP! PLEASE HELP ME :)

Mathematics

2 answers:

Nuetrik [128]2 years ago

7 0

<h3>Answer: 18/5 hours</h3>

Alternative formats are:

18/5 hours = 3 & 3/5 hours

18/5 hours = 3.6 hours

3.6 hours = 3 hours, 36 minutes

================================================

Explanation:

Let,

x = time it takes for Blake to do the job alone

y = time it takes for Ned to do the job alone

z = time it takes to do the job if they work together

In this case,

x = 9, y = 6 and z is unknown which we want to solve for.

The equation to solve is

1/x + 1/y = 1/z

So,

1/x + 1/y = 1/z

1/9 + 1/6 = 1/z

18z(1/9 + 1/6) = 18z(1/z)

18z(1/9) + 18z(1/6) = 18z(1/z)

2z + 3z = 18

5z = 18

z = 18/5

It takes them 18/5 hours if they worked together.

----------------

Here's an alternative way to look at it

Blake takes 9 hours if he works alone, so his rate is 1/9 of a room per hour. Similarly, Ned's rate is 1/6 of a room per hour. Their combined rate is

1/9 + 1/6 = 2/18 + 3/18 = 5/18

So,

(total rate)*(total time) = 1

(5/18)*z = 1

z = 1/(5/18)

z = 18/5

----------------

Side note

18/5 = (15+3)/5

18/5 = 15/5 + 3/5

18/5 = 3 + 3/5

18/5 = 3 & 3/5

also,

18/5 = 3 + 3/5

18/5 = 3 + 0.6

18/5 = 3.6

and,

3.6 hours = 3 hours + 0.6 hours

3.6 hours = 3 hours + (0.6*60 minutes)

3.6 hours = 3 hours + 36 minutes

3.6 hours = 3 hours, 36 minutes

Lana71 [14]2 years ago

5 0

Answer: The answer is 15

Step-by-step explanation: because 9+6 =15

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Vadim26 [7]

Answer:

9(n + 22) ≤ -15

Step-by-step explanation:

9 times the sum of a number and 22 is at most −15

Let n = number

Times = multiplication

Sum = Addition

9 * n + 22

We must add parenthesis on the end on 22 and before n

We must do this because it says 9 times the sum of a number and 22 which means that 9 is being multiplied by both n and 22

We would have 9(n + 22)

9(n + 22) is at most -15

At most meaning that -15 is the highest number that 9(n + 22) can equal

Because it says at most 9(n + 22) can equal -15 or anything less than -15

So at most can be replaced with ≤

9(n + 22) ≤ -15

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allochka39001 [22]

Answer:

The constant of variation is $1.50

Step-by-step explanation:

Given

Point 1 (1,2)

Point 2 (5,8)

Required

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Though the graph would have assisted in answering the question; its unavailability doesn't mean the question cannot be solved.

Having said that,

the constant variation can be solved by calculating the gradient of the graph;

The gradient is often represented by m and is calculated as thus

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By substituting values for x1,x2,y1 and y2; the gradient becomes

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