Answer:
Joint variation says that:
if
and 
then the equation is in the form of:
, where, k is the constant of variation.
As per the statement:
If x varies jointly as y and z
then by definition we have;
......[1]
Solve for k;
when x = 8 , y=4 and z=9
then
Substitute these in [1] we have;

⇒
Divide both sides by 36 we have;

Simplify:

⇒
to find z when x = 16 and y = 6
Substitute these value we have;

⇒
Multiply both sides by 9 we have;

Divide both sides by 12 we have;
12 = z
or
z = 12
Therefore, the value of z is, 12
Answer:
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Step-by-step explanation:

Answer:

Step-by-step explanation:
6 and - 2 are the only two solutions to the required quadratic equation.
So, if the variable is represented by X then (X - 6) and (X + 2) will be the only two factors of the polynomial function.
Therefore, the equation is
(X - 6)(X + 2) = 0
⇒
If the leading coefficient of the equation is 3 then we can write the equation as
(Answer)
30 dozen carnations.
20 dozen roses.
This means she spends 550, but makes 640.
I hope this is right?