Answer:

Step-by-step explanation:
To write the equation of a line we need 2 points. We know:
- If the y-intercept of the line is -3 then the point is (0,-3).
- If the x-intercept of the line is -4.5 then the point is (-4.5,0).
Using these two point, we will find the slope and then substitute it into the point slope form
with a point.
Slope: 
This decimal is -2/3. We will now substitute -2/3 and (0,-3) into the point slope form.

Given at you have an equilateral triangle, all sides have the same length.
Therefore,
First side 2x-7 = Second side x+y-9 = Third side y+5
Let us look at the second and third sides for now:
x+y-9 = y+5
x = y+5 - (y-9)
x = y-y+5+9
x = 14
Then we look at equating the first and third sides:
2x-7 = y+5
y = 2x-7-5
Substitute x =14 in the equation above:
y = 2(14)-7-5
= 28-7-5
= 21-5
= 16
The length of the third side is:
y+5 = 16 +5 = 21
Given that the length of each sides are the same in an equilateral triangle, all sides have the length 21cm.
Answer: I am going to put a link
maybe its going to help you?
Step-by-step explanation:
http://s3.amazonaws.com/illustrativemathematics/illustration_pdfs/000/001/217/original/illustrative_mathematics_1217.pdf?1390751150
Answer: it is 12 the second one