The metro train costs $6.30 round trip to ride to work each day. you work 4 days a week (16 days a month). if you can get a monthly pass for $78, how much can you save by buying the pass? $20.40$18.80$24.20$22.80

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.