Two points A and B were fixed on fixed on opposite bank of a river. The levels was setup near A and the staff reading on A and B were observed as 1.800 m and 1.300 m, respectively. Thereafter level was setup near B and staff readings observed on B and A were found to be 0.350 m and 0.850 m, respectively. If the R.L. of A is 101.500 m, then R.L. of B is: