Short Answer: 18 minutes
Remark
The answer to this problem is less than the smallest time of the two people working together. that fact lets out C and D (38 minutes and 75 minutes). Now you have to choose 15 minutes and 18 minutes. There's a method. No guessing needed.
Givens
Let the time for Sophie = S
Let the time for Simon = M
Let the job to completion = 1
S = 45 minutes
M = 30 minutes
Step One
Convert minutes to hours.
45 minutes = 45 / 60 = 3/4 hour = 0.75 hour
30 minutes = 30 / 60 = 1/2 hour = 0.50 hour
Step Two
Set up the Equation
The formula is a form of job / hour.
Let the time = t that they both have to work
job = 1 in these problems.
1/S + 1/M = 1/t
1/0.75 + 1/0.5 = 1/t
Solve
1 ÷ 0.75 = 1.33333
1 ÷ 0.5 = 2
1.3333 + 2 = 3.33333
3.3333 = 1 / t Multlply both sides by t
3.3333*t = 1
t = 1 / 3.333333333
t = 0.3 of an hour
1 hour = 60 minutes
0.3 hours = x Cross Multiply
x = 60 * 0.3
x = 18 minutes
Answer working together it took them 18 minutes <<<<<
Tim spends 500 minutes at the school.
Step-by-step explanation:
Given,
Time for lunch = 45 minutes
Time for study hall = 45 minutes
Total = 45+45 = 90 minutes
This represents 18% of the total minutes Tim spend at school.
Let,
x be the total minutes Tim spend at school.
18% of x = 90 minutes

Dividing both sides by 0.18

Tim spends 500 minutes at the school.
Keywords: percentage, division
Learn more about division at:
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Y=-5.11111 how I solved it is in the picture attached
The inequality |t - 72| ≤ 2 represents the target temperature for a laboratory is 72° Fahrenheit, and it can vary by up to 2° option (D) is correct.
<h3>What is inequality?</h3>
It is defined as the expression in mathematics in which both sides are not equal they have mathematical signs either less than or greater than, known as inequality.
The question is incomplete.
The complete question is in the picture, please find the attached picture.
We have:
The target temperature for a laboratory is 72° Fahrenheit. It can vary by up to 2°.
Target temperature = 72 degree Fahrenheit
It can vary by up to 2°. (the highest limit)
The temperature in the laboratory represented by t
Now,
inequality represents this situation is:
|t - 72| ≤ 2
Thus, the inequality |t - 72| ≤ 2 represents the target temperature for a laboratory is 72° Fahrenheit, and it can vary by up to 2° option (D) is correct.
Learn more about the inequality here:
brainly.com/question/19491153
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Answer:14
Step-by-step explanation: