20. Suppose consumers will demand55units of a product when the price is$16.30per unit and20units when the price is$21.30each. Find the demand equation, assuming that it is linear. Find the price per unit when45units are demanded.

Find the demand equation, where p is the price per unit and q is the quantity of units demanded.

p=?

21The demand function for a manufacturer's product isp=f(q)=0.16q+304,wherepis the price (in dollars) per unit when units are demanded (per day).Find the level of production that maximizes the manufacturer's total revenue and determine this revenue.What quantity will maximize the revenue?

q=? units

22 .Solve the system of equations using the substitution method.

r9s=0

3r8s=38

Select the correct choice below and fill in any answer boxes present in your choice.

A.

The solution of the system is ?.(an ordered pair.)

B.

There are infinitely many solutions.

C.

There is no solution.

23 Solve the system algebraically.

6x-4y=44

5x=3y=-14

Select the correct choice below and, if necessary, fill in the answer box of your choice.

A.

The solution isx=?and y=?

B.

There are infinitely many solutions of the form x=? and y=r. (Simplify your answer. an expression using r as the variable.)

C.

There is no solution.

25.A supply equation and a demand equation for a product are given below. If p represents price per unit in dollars and q represents the number of units per unit of time, find the equilibrium point.

supply: 35q-2p+230

Demand:65q+p-775

The equilibrium point (q,p) is? an ordered pair.)