First see if there is a constant rate of change...
(344.8-346)/(2-0)=-0.6
(343-344.8)/(5-2)=-0.6
So the rate is constant which means this is just a line of the form y=mx+b
m=-0.6 and since we see that (0,346) we know the y-intercept, "b", is 346 so our line is:
y(x)=-0.6x+346
y(4)=343.6 ft
y(9)=340.6
