51,000
5 in the ten thousands,
The thousands value is 1, the hundreds is 4 (less than 5 so we round down)
Justify means plug answer in and verify
so distribute 8(3-7x)=24-56x
143=7+24-56x
143=31-56x
minus 31 both sides
112=-56x
divide both sides by -56
-2=x
justify
plug it back
143=7+8(3-7x)
143=7+8(3-7(-2))
143=7+8(3-(-14))
143=7+8(3+14)
143=7+8(17)
143=7+136
143=143
true
x=-2
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 <<<<<
After thorough researching, if a jet in calm air conditions travels with velocity vector (389, 389) and the wind velocity (in mph) at the plane’s cruising altitude is given by (0, 50), then the plane’s true speed is 600 mph. The correct answer to the following given statement above is with the letter C.
I can help!! But could you tell me what the equations are?
