If I'm not mistaken, the x-intercept is found when the line crosses the y-axis (so the value of y would be 0). Since the x-intercept is 7, that basically means that when y is 0, x will be 7.
The x-intercept is where the graph crossed the “x-axis” I believe, hence the name “x-intercept.” We know x=7, so we can write “(7, y) instead of (x, y). For “y” there is not enough information given to know what “y” is, so I just wrote y.
