Explanation:
Take a look at this graph (sorry, it's small). The graph shows three data points, (0, 1), (2, 6), and (4, 8). The line is called the "line of best fit" or "regression line."
The equation for the line is y = 1.75x + 1.5 .
The data did not include a point for x = 3, but it can be predicted by finding the y-coordinate on the line that corresponds to x = 3.
Substituting x = 3 into the line's equation gives
y = 1.75(3) + 1.5 = 6.75
That's the predicted value of y for x = 3 given the linear relationship shown.