we know that
A relationship between two variables, x, and y, represent a direct variation if it can be expressed in the form 
or 
where
k is the constant of variation
in this problem we have
the point 
so
substitute
therefore
<u>the answer is</u>
Answer:
Step-by-step explanation:
(-7,1) is a solution to the inequality y<0.5x+9
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 <<<<<
The positions of the sun, earth and shooting star form a right angled triangle, where distance between earth and sun is 'y', and the angle 'x°' is given
Now, in a right angled triangle using trigonometry, we can determine a side of the triangle is one of the sides and one of the angles is known
Here, if we use cos x = 
we can determine the distance between the shooting star and the sun. This can be done because we know that the base is 'y', the angle is x° and the hypotenuse represents the distance between the sun and the shooting star
Note: cos values for each x are definite.
