Step-by-step explanation:
Since
varies directly as
we can write the relation as

where k is the constant of proportionality.
a) To solve for the k, we substitute the given values:


b) The equation relation x and y can be written as

c) When y = 9,

Answer:
-3
Step-by-step explanation:
divide 7 on both sides -21/7 = -3
w=-3
Third length =
12-7 = 5
12+7 = 19
Third length can be only in this range
5Means the third length must be greater than 5 and less than 19.
Hope this helps!