the project includes a $6$ft $($Hw$)$ cantilever retaining wall. The bottom of the wall footing will be at a depth of $8$ft below ground surface. The backfill behind the wall is sandy material with a unit weight of $105$ pcf and angle of internal friction of $30$ degrees. The backfill is level. The wall is $12$ inches in thickness at the top and bottom. the footing is $18$ inches in thickness. the toe extension is $1\mathrm{.}50$ ft and the heel extension is $4$ft$.$ Calculate the safety factor against sliding. Use Rankine method

Please write neat and include formulas you use. Thank you, I will upvote! :)