Which information is necessary to solve this problem? the prestons' car gets 28 miles per gallon of gasoline. their gasoline tank holds 18 gallons. their trip will be 400 miles long. how many gallons of gasoline will they use?

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.