A $2000k\frac{g}{h}$ of meal containing $26$ mass$\%$ oil$($C$)$ has been extracted with $2100k\frac{g}{h}$ of benzene$($B$).$ The final underflow leaving the countercurrent cascade contains $0\mathrm{.}015$ mass fraction of oil and $0\mathrm{.}3175$ mass fraction of solvent. The solvent benzene has $0\mathrm{.}005$ mass fraction oil in it$.$ The overflow is solid free. Compute the mass fraction of overflow leaving the cascade and the number of ideal stages required by using Ponchon$-$Savarit diagram. The equilibrium data are given as follows:

$\backslash$table$[[Y_c,Z_v,x_c,Z_l$