Of the 30 students participating in a science fair, 12 are growing plants, 8 are making modelvolcanoes, and the rest are doing other projects. what is the ratio of students doing other projectsto the total number of student participants?

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)