At the end of a snow storm, Tristan saw there was a lot of snow on his front lawn. The temperature increased and the snow began to melt at a steady rate. After the storm,
the snow started melting at a rate of 0.75 inches per hour and it is known that 4 hours
after the storm ended, the depth of snow was down to 9 inches. Write an equation for
S, in terms of t, representing the depth of snow on Tristan's lawn, in inches, t hours
after the snow stopped falling.

The linear equation that represents the depth of snow on Tristan's lawn, in inches, t hours  after the snow stopped falling is:

A linear function in the model will have the following format:

In which:

The snow melts at a rate of 0.75 inches per hour, thus and:

After 4 hours, there were 9 inches, that is, when , and this is used to find S(0).

Hence, the equation is:

A similar problem is given at link

Step-by-step explanation:

Given: The snow started melting at a rate of 0.75 inches per hour and it is known that 4 hours  after the storm ended, after the storm ended, the depth of snow was down to 9 inches.

Snow melted in 4 hours =

Initial depth of snow = 9 + 3 inches = 12 inches.

Now, depth of snow on Tristan's lawn = Initial depth -0.75(Number of hours)

Let S(t) be the depth of snow on Tristan's lawn, in inches, t hours after the snow stopped falling.

Then,