$4)$ Leveling from BM A to BM B to BM C gives differences in elevation $($in feet$)$ of $25\mathrm{.}34,+20\mathrm{.}45,$ and $+8\mathrm{.}12$ respectively. Distances between benchmarks are:

AB $=2200$ ft$,$ BC $=3100$ ft$,$ and CA $=3700$ ft$.$

True elevations of the benchmarks are A $=865\mathrm{.}67$ ft$,$ B $=819\mathrm{.}35$ ft$,$ and C $=827\mathrm{.}47$ ft$.$ What is the adjusted elevation of BM W$?(15$ points$)$