Triangles have 3 vertices. The total is 21 vertices. 21 / 3 = 7. He drew 7 triangles.
Answer:

Step-by-step explanation:
Mod of any number represents the absolute value of the number.
Therefore,
= 2.25




Now we can arrange these numbers in ascending order.
-2.25 < -1.25 < 0.75 < 1.25 < 1.75 < 2.25
Therefore, 
I'm not sure for number one, but for number 2 the answer to that one is the second tallest on the chart or on the histogram. For number 3 I'm not sure because i cant see the numbers there too blurry. I'm sorry but i hope i got the second one correct.
First one is 4^2 or just 16.
Second one is using√ So what you want to do is 2√16
Hope this helps