Step-by-step explanation:
If a variables varies jointly, we can just divide it by the other variables in relation to it.
For example, since p variables jointly as q and square of r, then

where k is a constant
First, let find k. Substitute p= 200
q= 2, and r=3.



Now, since we know our constant, let find p.

Q is 5, and r is 2.



Answer:
I think the answer is 81.
Step-by-step explanation:
Vertical angles are congruent.
x + 3 = 84
- 3 = -3
--------------
x = 81
We can write two equations for this. x = each minute of calls
Plan A = .1x + 16
Plan B = .14x
Make the two equations equal each other, so we can find when they are the same.
.1x + 16 = .14x
Subtract .1x from both sides
16 = 0.04x
Divide by 0.04 to get x by itself
400 = x.
Earlier, we set x as each minute of calls. This means that after 400 calls, Plan A and Plan B will cost the same.
To find the cost, substitute 400 into both equations by themselves.
Plan A cost = .1x + 16
Plan A cost = .1(400) + 16
Plan A cost = 40 + 16
Plan A cost = $56
Plan B cost = .14x
Plan B cost = .14(400)
Plan B cost = $56
Final answer: After 400 calls, Plan A and Plan B will both cost $56.
The average rate of change of function describes the average rate at which y-value ( or f(x)) is changing with respect to changing x-value.
The average rate of change=

In this exaple is x1=4 and x2=7 and we will find y1 and y2:
y1=3(4-3)²+4=3*1+4=7
y2=3(7-3)²+4=3*16+4=48+4=52
Finally:

Answer: The average rate of change for f(x) from x=4 to x=7 is 15.