Final answer:
Without additional information regarding the length of QR or RS, it's impossible to determine the measure of QR with QS being 155.
Step-by-step explanation:
The given problem where point R is between Q and S and we know the total distance QS to be 155 does not provide enough information to determine the distance of QR explicitly. To solve completely, additional information such as the specific measure of QR or RS would be required. If the student has more information about how QR relates to QS or RS, please provide that so a precise answer can be given.
In general, if R is between Q and S on a line segment, then QR + RS = QS. Without the length of either QR or RS, we cannot determine the exact measure of QR.