A lake near the Arctic Circle is covered by a 2-meter-thick sheet of ice during the cold winter months. When spring arrives l, the warm air gradually melts the ice, casings it’s thickness to decrease at a constant rate. After 3 weeks, the sheet is only 1.25 meters thick.

Let y represent the ice sheet’s thickness (in meters) after x weeks.

Complete the equation for the relationship between the thickness and number of weeks.