$F_{\perp }=F_c\cos \alpha$

$F_{\parallel }=F_c\sin \alpha$

$T=f{F}_{\perp }$

$F=F_{\parallel }+T$

$F=F_{\parallel }+f{F}_{\perp }$

$F=F_c\sin \alpha +f{F}_c\cos \alpha$

$F=F_c\left(\sin \alpha +f\cos \alpha \right)$

$F=mg\left(\sin \alpha +f\cos \alpha \right)$

$W=\vec{F}\circ \vec{s}$

$W=F\cdot s$

$W=mg\left(\sin \alpha +f\cos \alpha \right)\cdot s$

$W=mg\left(\frac{h}{\cancel{s}}\cdot \cancel{s}+f\frac{l}{\cancel{s}}\cdot \cancel{s}\right)$

$W=mg\left(h+fl\right)$

$W=20\mathrm{kg}\cdot 10\frac{\mathrm{m}}{{\mathrm{s}}^2}\cdot \left(20\mathrm{m}+0,35\cdot 5\mathrm{m}\right)=$

$=20\mathrm{kg}\cdot 10\frac{\mathrm{m}}{{\mathrm{s}}^2}\cdot \left(20\mathrm{m}+1,75\mathrm{m}\right)=$

$=20\mathrm{kg}\cdot 10\frac{\mathrm{m}}{{\mathrm{s}}^2}\cdot 21,75\mathrm{m}=4350\mathrm{J}$