The segment midpoint divides a segment into 2 halves by definition.
By the Segment Addition Postulate, you can add two adjacent segments to get the total length of the segment.
Given that RS=14
That means that 14 is 1/2 if the total segment length, so we know that segment RT is also = to 14 to make the other half.
We have two lengths that are 14, so we simply add them together to find the total segment’s length.
14+14=28.
The total line segment is 28.