Susan wants to make 2 square flags to sell at a crafts fair. The fabric she wants
to buy is 5 meters wide. She doesn't
want any fabric left over. What's the
least amount of fabric she should buy?

10 meters

Step-by-step explanation:because they are square and they would have to be 5 meters long and she dose not want any left over so...

for finding the midpoint of any given 2 pair of points simply add the respective x coordinates with other x coordinate and the y coordinate with other y coordinate and divide them by 2

in your question it will be :

(3+1)/2 for the x coordinate of mid point i.e 2

[8+(-4)]/2 for the y coordinate of midpoint i.e 2

so coordinates of mid point of points (3,8) and (1,-4) will be (2,2)