Answer:
the elevation at point X is 2152.72 ft
Explanation:
given data
elev = 2156.77 ft
BS = 2.67 ft
FS = 6.72 ft
solution
first we get here height of instrument that is
H.I = elev + BS Â ..............1
put here value
H.I = Â 2156.77 ft + 2.67 ft Â
H.I = 2159.44 ft
and
Elevation at point (x) will be
point (x) Â = H.I - FS Â .............2
point (x)  = 2159.44 ft  - 6.72 ft
point (x) Â = 2152.72 ft