Final answer:
The y-intercept represents the value of the dependent variable when the independent variable is zero.
Step-by-step explanation:
The y-intercept, a, of a graph tells us the value of the dependent variable (y) when the independent variable (x) is equal to zero.
In the context of the equation mentioned in Item 3, where the y-intercept is 50, it represents the point on the graph where the dependent variable (y) would be 50 when the independent variable (x) is zero.