In one dimensions (i.e. with standard numbers and not points with more coordinates) the midpoint is the same as the average.
The average of two numbers is their sum divided by two.
So, we have -4+20=16. Divide this by two to get 8.
Say for example, you have the improper fraction 18/7
The first step is to find out how many times 7 fits into 18
This looks like flipping the fraction, 7/18 = 2 whole times with 4 parts left over
The 4 left over gets put in front of the original number (7) to give 2 4/7
To check if you have done it correctly, multiply the whole number (2) by the denominator ( 7 ) and then add the numerator.
2 x 7 = 14 + 4 = 18
Hope this helps
