Question

Find the slope of the line y=8

Answer 1

The slope is 0 and it crosses the y- axis at 8

Answer 2

If y=mx+b, and the equation is y=8. The y value is always 8 since x is not in the equation. So it's a horizontal line which crosses y=8. Since the gradient by definition is rise over run, and a horizontal line has no rise; the gradient is 0.