The total revenue r (in dollars) is directly proportional to the number of units sold x. when 25 units are sold, the total revenue is $300. write a mathematical model that relates the total revenue r to the number of units sold x.

Step-by-step explanation:

The total revenue R (in dollars) is directly proportional to the number of units sold x. This means that

R is directly proportional to x

If we introduce a constant of proportionality, k, it becomes

R = kx

When 25 units are sold, the total revenue is $300. We will substitute the value of R and x to get a value for k. It becomes

300 = 25k

K = 300/25 = 12

The mathematical model that relates the total revenue R to the number of units sold x will be

R = 12x