a segment is partitioned at a ratio of 1:3, then the point is one-fourth of the distance from (-4,-1) to (2,7).
To compute the x-coordinate of that point, you will need to compute one-fourth of the x-distance between 2 and -4 then add it to -4: (2--4)/4 = 1.5; 1.5 + -4 = -2.5.
To compute the y-coordinate of that point, you will need to compute one-fourth of the y-distance between 7 and -1 then add it to -1: (7--1)/4 = 2; 2 + -1 = 1.