How do i figure out the instantaneous rate of change with given graph and it says find the rate at t = 6 s

Answer 1

I would look at rate of change (slope) of the graph.

If the graph is horizonal, rate of change is zero
If the graph is sloping, the slope is the rate of change.

Answer 2

Do i have to make a tangent line?

Answer 3

Also, do i have to use numbers like 5.99 and 6.01 to find the rate of change @ t = 6s