Ms. lieber takes 4 hours to drive 210 miles from her home to yosemite national park . if miss lieber's average speed for the first two hours is 60 miles per hour, find her average speed for the last 2 hours

Suppose that the price p, in dollars, and the number of sales, x, of a certain item follow the equation 4 p plus 4 x plus 2 pxequals56. suppose also that p and x are both functions of time, measured in days. find the rate at which x is changing when xequals2, pequals6, and startfraction dp over dt endfraction equals1.5.