Find the equation of the line.
Use exact numbers.

y = -1/3x +5

Step-by-step explanation:

The slope intercept form is y = mx+b where m is the slope and b is the y intercept

The y intercept is 5  ( where it crosses the y axis)

The slope is

m = (y2-y1)/(x2 -x1)

We need two points on the line ( 0,5) and (3,4)

m = (4-5)/(3-0)

   = -1/3

y = -1/3x +5

Start by finding the b or the y-intercept.

This is the point where the line crosses the y-axis.

Our y-intercept is (0,5) or just 6.

From here, we look for clear cut points on the line.

Notice that if we go down 1 unit and to the right 3 units,

our point will end up exactly in the middle of the cross.

So our slope is -1/3.

So the equation is -1/3x + 5.

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50