Asked by Ali

Assume that a theodolite sits between Point-A (BM) and Point-B. If the elevation of Point-A is 23.56m, the RR at BS is 1.4m, the RR at IS is 1.86m, and the RR at FS is 2.3m. Then, the elevation of HI is equal to:
oobleck
maybe you should describe the diagram, and explain what all those two-letter abbreviations mean.