Check the picture below, let's use those two points on the line to get its slope.

On the 4th question I can’t tell if those are dots or arrows on the line above “AN” when it says “B lies on AN”, if those are 2 dots on the little line don’t check it, if they are 2 little arrows on the line then check the box, but other than that the rest of the checked are right!!
Answer:
Adult tickets =125
Child tickets = 128
Step-by-step explanation:
Let the number of adult and children tickets sold be x and y respectively
So that
x+y= 253--------1
Since total sales/receipt is $2,771
And given that tickets for a dance recital cost $15 for adults and $7 for children hence
15x+7y= 2771-------2
Solving equation 1 and 2 simultaneously we have
x+y= 253---------------1
15x+7y= 2771----------2
Let us multiply equation 1 by 15 to get equation 3 to eliminate x and subtract equation 2 from 3
15x+15y=3795---------3
-{15x+7y= 2771----------2
0+8y=1024
8y= 1024
y= 1024/8
y= 128 tickets
So solve for x let us put y= 128 in equation 1
x+ 128=253
x=253-128
x= 125 tickets
3a+b+c
The perimeter is two times one side (to account for the opposite) and two times the adjacent side. So if the sides would be x and y, the perimeter would be 2*x + 2*y.
So, knowing that the sum is 16a+8b-6c, if we subtract the given side 5a+3b-4c from this, what remains is two times the "other" side:
16a+8b-6c - 2*(5a+3b-4c) =
16a+8b-6c -10a-6b+8c =
6a+2b+2c
half of that is
(6a+2b+2c)/2 = 3a+b+c