Suppose the price p, in dollars, and number of sales, x, of an item is related by 5 8 6 50 p x px + + = . If p and x are functions of time, measured in days, find the rate at which x is changing when x = 15, p = 2.90 and dp/dt = -1.15

According to the information of the problem  x = 15 , p=2.90 and dp/dt = -1.15

then  

Step-by-step explanation:

Since everything is changing with respect to time and are related according to the following equation

We need to find the implicit derivative with respect to the time. And we get the following.

is what we don't know, so we solve for it and get

Now. According to the information of the problem  x = 15 , p=2.90 and dp/dt = -1.15

then  

21

jk it's 20

step-by-step explanation: