Question

how can you put -4/5 on the number line

Answer 1

divide the space between one and zero into five and put it on the section closest to one but not on it

Answer 2

Draw a number line. Make sure that the values -1 and 0 are on it. In between these two values, cut the interval into 5 equal slices. It doesn't have to be perfect. Just the general idea is what counts. Place your pencil at 0 and then count four spots to the left until you arrive at -4/5

See the attached image for visual details.