At the end of a snowstorm, Idil had 17 inches of snow on her lawn. The
 temperature then increased and the snow began to melt at a constant
 rate of 1 inch per hour. Assuming no more snow was falling, how much
 snow would Idil have on her lawn 5 hours after the snow began to
 melt? How much snow would Idil have on her lawn after t hours of
 snow melting?