Where:

${}^{\text{'}}=[20**N_{60}(\frac{p_a}{{}^{\text{'}}}{)}^{0\mathrm{.}5}{]}^{0\mathrm{.}5}+20$

${}^{\text{'}}=$ Friction Angle

$N_{60}=$ SPT N value corrected for hammer energy

$p_a=$ Atmospheric Pressure $(2116\mathrm{.}21$ psf$)$

${}^{\text{'}}=$ Effective overburden stress

PLEASE DO STEP BY STEP AND INCLUDE CALCULATIONS