A levelling is carried out to establish the reduced level (RL) of point R with respect to the bench mark (BM) at P. The staff reading taken are given below
Staff Station | BS | IS | FS | RL |
P | 1.655 | - | - | 100.000 |
Q | -0.950 | - | -1.500 | - |
R | - | - | 0.750 | ? |