If you already have an equation, all you have to do is locate the slope and look after it. But if it's in a graph, it's where the line is crossing the y-axis.
An example of the equation would be
y=2x+3
y=mx+b
2 would be m which is slope
and 3 would be b which is the y-intercept
Answer:

Step-by-step explanation:
The volume of a sphere is given by :

The rate of change of volume means,

We have, 
So,

So, the volume is increasing at the rate of
.
The answer is 954, have a good day
Writing and solving an equation of ratios would seem to be the best way to go.
0.045 sec 3 sec
------------- = ------------
1 image x
Then 0.045x = 3, and x = 66 2/3 images, best rounded down to 66 images.