A lake near the arctic circle in covered by a 2-meter-thick sheet of ice during the cold winter months. When spring arrives, the warm air gradually melts the ice, causing its thickness to decrease at a constant rate. After 3 weeks, the sheet is only 1.25 meters thick Let y represent the ice sheets thickness (in meters) after x weeks

y (x) = - 0,25*x + 2

Step-by-step explanation: If ice thickness decrease at a constant rate (for slope of a curve to be constant curve have to be a straight line.

Equation for straight line is

y (x) = m*x + b

where y is tickness as function of time x is time, m slope and b the interception with y axis

We need to find m and b

b when x = 0 y (x) = 2 as from problem statement

therefore b = 2

After 3 weeks y (x) = 1.25

Then 1.25 = m * (3) + 2

3m = - 0,75

m = - 0,25

Finally

y (x) = - 0,25*x + 2