The direct variation between x and y may be written as,
y = kx
where k is the constant of variation. From the first set of values of the variables,
12 = k(8)
the value of k is 1.5. Substituting the next set to the same equation,
y = 1.5(14)
The value of y is 21.
Answer:
216 cookies
Step-by-step explanation:
From the question,
Let the total cookies in the first place be x cookies.
Their ratio = 5:12:9
Total = 5+12+9 = 26.
Weiming share = (5/26)x = 5x/26
If weiming sold 28 cookies
⇒ (5x/26)-28
⇒ (5x-728)/28
Hence Weiming new share = (5x-728)/28 cookies
The new ratio is 1:8:6
The total cookies becomes = x-28
Therefore,
(1/15)(x-28) = (5x-728)/28
(x-28)/15 = (5x-728)/28
Crossmultiply
28(x-28) = 15(5x-728)
28x-784 = 75x-10920
Collect like terms
28x-75x = -10920+784
-47x = -10136
x = -10136/-47
x = 215.7
x ≈ 216 cookies
You need to see which is more

On the unit cirlce, the cosine of an angle is negative whenever the angle falls in the interval

.
If you recall your special triangles, this cosine occurs for angles of

and

.
More generally, this occurs for

and

, where

is an integer.