Question

HELP PLEASE!

Answer 1

A table can be used to find the rate of change by giving you a visual representation of how the operation changes over time for example in the link i'm about to post you can see how much more money is earned as more cars are washed, it is showing how much money is being made OVER TIME, hope this helps :)

now to answer your second question, say you would like to know how many miles Tracy ran over a course of 2 hours, the x axis would be the miles and the y axis would be the time, then you would plot the different points on the graph showing the rate at which she is running
'
to answer your last question a linear interval would be a sequence of numbers that when places on a number line they will form a line, a nonlinear interval is a sequence of numbers that don't make a line because there are inequities meaning the numbers in the sequence are all over the place 

Hope this helps and i will post the pictures so you can have a visual representaion

Answer 2

In a table the numbers in the Y column can help you see the change of rate by subtracting the one on top by the one on the bottom. 
example below. You ca see that the number that it gives you it is always the same, therefore that is the change of rate or slope. 

In a graph select 2 points and divide how many numbers to go up and how many in the x axis. then divide them rise÷run=slope

The difference between a linear interval is that the rate of change is always the same. That is why it is a line and not a curve or a circle etc.