6. No it is not equilateral because a. All the angles should be congruent (60) and as we can tell, they are not, and b. you should never assume measurements.
8. GF is the longest because the angle for that side (GFH) is smaller than the others, so it means it has a longer side.
Your answer for 9 is wrong. The answer is yes because the largest angle = the largest side.
10. AC because largest angle = largest side
11. Literally the same thing as 9 and 10. Largest angle = largest side
For this case we have that by definition, the equation of a line of the slope-intersection form is given by:

Where:
m: It is the slope of the line
b: It is the cut point with the y axis
By definition, if two lines are perpendicular then the product of their slopes is -1.
If we have: 

Thus, the equation is of the form:

We substitute the point:

Finally, the equation is:

Answer:

Celculate the figures by using the numbers,with letters
In this case, i think you just need to divide the amount of telephone subscription and divide it among 100 people
For example, let's say that there is around 2,000,000 subscription for 100,000 users.
The amount would be : 2,000,000 / 1,000
= 2,000 number of mobile per 100 people
hope this helps