Bill travels west on interstate 80 from summerville. sally leaves carlton city and travels on i-80 in the same direction as bill. bill's distance in miles from metro city is given byb(t) = 120 – 60tand sally's distance in miles from metro city is given bys(t) = 135 – 70, where t is the number of hours since noon. write an expression for the distance separating bill and sally and find their separation at 2: 00 pm.