Suppose that the price p, in dollars, and the number of sales, x, of a certain item are related by 5p + 5x + 2px = 90. If p and x are both functions of time, measured in days. Find the rate at which * d x is changing when x = 4, p = 5, and 1% = 1.5. I The rate at which x is changing is El E (Round to the nearest hundredth as ne i i 1; day(s) per sale. sale(s) per day. day(s). sale(s)