Find the percentage rate of change of f(x) at the indicated value of x. f(x) = 159 +54x; x = 8 The percentage rate of change of f(x) at x = 8 is %. x (Type an integer or decimal rounded to the nearest tenth as needed.) Use the price-demand equation below to find the values of p for which demand is elastic and the values for which demand in inelastic. Assume that price and demand are both positive x=f(p)=245 - 35 Demand is elastic for all values of p in the interval Type your answer in interval notation)