To solve this, we need to understand Slope Intercept Form (SIF), as well as how to graph a line.
SIF is the standard equation of lines on graphs. It is "y=mx+b" where m is the slope and b is the y-intercept. The y-intercept is the value of y when x is 0.
To find the y-intercept (which we will need to form the equation), we should simply graph the line. This will let us visualize the y-intercept, and overall make it easier to understand.
To graph a line, we should start with the point we have (that being (3, 3)) and follow the slope with rise/run. This means in this case, we will go right 2 for every 1 up, or 2 left for every 1 down.
Below I have attached a graph to help you see how to graph this, which we will get our equation from. The highlighted area is our y-intercept. The red circle shows our original point (3,3), and the blue dots show our slope.
Using the graph, we can see the equation for this line is
y=1/2x+1.5.
To find the lateral surface area of a pyramid, you can find the area of each triangle, A = 1/2bh or A = 1/2lw, then multiply by the number of triangles, which would be based on the number of sides of the base; or you can take half the perimeter and multiply by the slant height.
Data:
x: number of months
y: tree's height
Tipical grow: 0.22
Fifteen months into the observation, the tree was 20.5 feet tall: x=15 y=20.5ft (15,20.5)
In this case the slope (m) or rate of change is the tipical grow.
m=0.22
To find the line's slope-intercep equation you use the slope (m) and the given values of x and y (15 , 20.5) in the next formula to find the y-intercept (b):

Use the slope(m) and y-intercept (b) to write the equation:

A) This line's slope-intercept equation is: y=0.22x+17.2
B) To find the height of the tree after 29 months you substitute in the equation the x for 29 and evaluate to find the y:

Then, after 29 months the tree would be 23.58 feet in height
C) In this case as you have the height and need to find the number of moths you substitute the y for 29.96feet and solve the equation for x, as follow:

Then, after 58 months the tree would be 29.96feet tall
The amount if the original cost of the head board is $12.24