Answer:
see the explanation
The graph in the attached figure
Step-by-step explanation:
<u><em>The correct question is</em></u>
Explain what the slope and intercept mean in each situation.
A graph represents the perimeter,y, in units, for an equilateral triangle with side length x units. The slope of the line is 3 and the y-intercept is 0
we know that
The linear equation in slope intercept form is equal to

where
m is the slope
b is the y-intercept
In this problem
y is the perimeter in units
x is the side length of a equilateral triangle
we have

substitute
The linear equation is
---> Is a proportional relationship because the line passes through the origin
see the attached figure to better understand the problem
<u><em>Explanation</em></u>
The slope is ---> 
That means
The ratio of perimeter of triangle to side length of triangle is 3:1
The y-intercept is 0
Remember that
The y-intercept is the value of y when the value of x is equal to zero
In this context
The y-intercept is the value of the perimeter when the value of the side length is equal to zero
so
The value of the perimeter is 0 when the value of side length is 0