I have the answer, however I need help with solving it$.$

So$=80\%$

$1\mathrm{.}19$ The following data pertain to an oil formation: $F$ vs$.$ relation given by Fig. $1\mathrm{.}10$; I vs$.S_w$ relation given by Fig. $1\mathrm{.}18$; formation resistivity measured in situ by an appropriate logging device $=7*m$; formation water resistivity determined from water sample chemical analysis $=0\mathrm{.}01*m$; and formation porosity from an appropriate logging device $=17\%.$ Give your best estimate of the formation oil saturation.