Itook a picture of numbers 20 and 21 because i do not get it says draw a horizontal number line from 2 to 3 to represent each set of numbers well i'm 20 and 21 on my picture it says its at the numbers if you can

It simply means to put them in order from 2 to 3

You could change all of them to 20ths to put them in order but since they all begin with 2 lets do it differently.  Think of each fraction as a test score.
It is obvious that the person who got 3 out of 20 did the worst so 3/20 is lowest
9 out of 20 is a little less than 1/2 the test right so it comes 2nd
No other score is less than 1/2 So 1/2 comes 3rd
11 out of 20 is just a little better than 1/2 so it comes 4th
Finally 4 out of 5 is the best score so it comes 5th
Here is the order from 2 to 3
2        2 3/20       2 9/20    2  1/2    2 11/20     2 4/5     3 
Now for the decimals
Let's put them one above the other to start and add zeros to make them all the same length:
2.500
2.125
2.375
2.875
It easy to see now that the order from least to greatest is:
2    2.125      2.375      2.5(00)  2.875    3

The directions to put them on a horizontal number line means simply to draw a line that passes through each of the answers  above.  See my document to see a skeleton of what it might look like.