Answer:

Step-by-step explanation:
Given that the triangles are similar then the ratios of corresponding sides are equal.
To determine the scale factor calculate the ratio of corresponding sides, that is
=
= 
Let call it x
x/4=4/2
->x=8
Answer:
The lines blue and green are perpendicular
Step-by-step explanation:
we know that
If two lines are perpendicular, then their slopes are opposite reciprocal (the product of their slopes is -1)
The formula to calculate the slope between two points is equal to

step 1
Find the slope of the blue line
we have the points
(-1,-3) and (0,3)
substitute


step 2
Find the slope of the red line
we have the points
(3,-3) and (4,2)
substitute


step 3
Find the slope of the green line
we have the points
(-4,-1) and (2,-2)
substitute


step 4
Compare the slopes
Blue line ----> 
Red line ----. 
Green line ---> 
so
The slope of the blue line and the green line are opposite reciprocal ( their product is equal to -1)
therefore
The lines blue and green are perpendicular
Answer— 45/15=3 so there is 3 classes with 15 students in each class? I didn’t really understand your question but I tried!
Hope it helped!