Question 41823
This problem involves the equation of a line.  The formula is y = mx + b
y = any value for y
m = the slope of the line
x = any matching value for x
b = the point where the line crosses the y-axis.

In your table, the "x" values are "the number of tickets."  The corresponding "y" values are the cost for that number of tickets.  
For example 1 ticket costs $1.50.  Two tickets cost $3.00, etc.
.
First, find the slope of the line using:
slope (m) = (y1 - y2)/(x1-x2)
I picked any two points from your table:
(1, 1.50) and (2, 3.00).  The first number is the x value and the second number is the y value. 
.
Slope = (1.50-3.00)/(1-2)= 1.5
.
Next plug in values for y = mx + b and solve for "b".  I picked the point (2, 3.00) again
.
3.00= (1.50)2 + b
3.00 = 3.00 + b
3.00 - 3.00 = b
0 = b (which is the value for the y-intercept)
.
Plug-in the values that we found for the slope and the y-intercept values into the equation for the equation of the line:
y = 1.5x + 0
or 
y = 1.5x 
.
Check by testing another point from your table.  Lets pick (4, 6.00)
6.00 = (1.5)(4) + 0
.
6 = 6

So what this table tells you is that for every ticket sold, the slope or price goes up $1.50. Using the slope-intercept formula helps to predict the cost of any number of tickets.  The cost ("y") of 135 tickets ("x") at $1.50("m")would be:

y = (1.5)(135) + 0
y = $202.50