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 <<<<<
First calculate the hourly rate, which is the difference of cleaning 2 and 1 rooms:
175-125=50
then calculate the initial value by subtracting the hourly rate from the "1 room" cost:
125-50=75
The initial cost might be something like driving to the place (which is only necessary once), while the rate covers work time or cleaning utensils used.
The answer is B sorry i was wrong
<span>1 perpendicular bisector divides 1 side of the triangle into two equal lengths at a 90 degree angle. So if there's is three perpendicular bisectors, then it splits all three sides the triangles into equal lengths.
Angle bisectors splits an angle of a triangle into two even degrees.
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<span>EX: if it is an equilateral triangle, each angle will be sixty degrees. Therefore, ONE angle bisector will split ONE of the angles into even degrees of thirty degrees. </span>
