The slope of the trend line is 0.90 ($900), which represents an increase in <em>salary</em> of $900 for every $1,000 increase in <em>annual tuition cost. (Third Option).</em>
<em><u>Recall:</u></em>
Slope of a trend line usually depicts a unit rate between two variables.
The equation of a trend line is usually represented in slope-intercept form as, <em>y = mx + b</em>.
Where, m is the slope, x and y are the two variables that are changing, while b is the initial value.
Given the equation representing the trend line as, s = 0.90c + 26.4
The slope of the trend line would be 0.90, which is $900.
This means that, there is an increase in <em>salary</em> of $900 for every $1,000 increase in <em>annual tuition cost. (Third Option).</em>