### Home > AC > Chapter 8 > Lesson 8.1.4 > Problem8-40

8-40.

Mary says that you can find an $x$-intercept by substituting $0$ for $x$, while Michelle says that you need to substitute $0$ for $y$.

1. Who, if anyone, is correct and why?

One way to view this is graphically: the $x$-intercept lies anywhere along the $x$-axis.

Michelle is correct. The $x$-intercept always has a $y$-coordinate of $0$ because it lies on the $x$-axis.

2. Use the correct approach to find the $x$-intercept of $-4x+5y=16$.

Substitute $0$ for $y$ and then solve for $x$.