$($a$)$ Check the stability $($overturning$,$ sliding, bearing capacity$)$ of the cantilever wall$-$backfill system shown in Figure $1,$ with the data given in Table $1,$ and state if the selected dimensions are safe or not $($Use Rankine's theory of earth pressures$).$

Figure $1.$ Cantilever retaining wall.

$x_3=0\mathrm{.}60m$

Base and front soil: ${}_2=20,$

$c_2=30$kPa,

${}_2=20k\frac{N}{m^3}$