Answer
The slope of the equation.
Step-by-step explanation
The general equation of line is y = mx + c, where (x,y) is a point on the line, m is the slope and c is the y-intercept.
When the line is in the equation above, we can explain the meaning of each term.
After recording the data plotting the line, Ted came up with the equation;
y = 300 + 0.45x.
Writing this in the form of y = mx + c we have,
y = 0.45x + 300.
m = 0.45 ⇒ This is the slope of the equation.