$"$In surveying field work. A tachometer $($same used at laboratory$)$ was sot up at the top of a hill with a known olovation of

the hill of $400m($MSL$),$ it was used to measure the elevation of a lower point $($B$).$

If the elevation difference between the top of the hill and point $B$ equals $10m$ and the horizontal distance between the

two points equals $50m.$

hair readings of the instrument:

offset reading $=2\mathrm{.}02m.$

lower hair reading $=1\mathrm{.}45m.$

Know that hoight of instrument $=1\mathrm{.}3m$

The middle hair reading on the instrument equals to $?$

Depending on previous given data, the angle of the inclined line of sight to point B for the?

The factor on the offset hair of the tachomotor would be$?$