The fraction 1 5/8 converted to improper is 13/8 so count 13 points to the right of the number line from 0. So that is where it falls.
Now if we are to find the opposite of a positive integer or fraction we are just to put a negative mark so it will be -1 5/8 or -13/8 in improper form. So just count 13 points to the left of the number line from 0 and that's your answer buddy!
But tbh this is actually an extensive and time taking process but if you follow this you can be sure of your answer. So the easier process is to see the whole and the parts of whole. As you can see there are 8 parts between each number so it means each number is divided into 8 parts and to make it easier the fraction shows that 1 5/8 has 8 parts for each to. So we will take the 1 of the 1 5/8 and skip 8 parts to the whole number 1. Then we will take the 5 from 5/8 and count 5 points from 1. That's the position of 1 5/8 on the number line. As for the opposite, add negativity sign and do just the same! And that's the answer!