Same direction (SD) opposite (OD)

$C = C_W + C_E. . .(SD)$

$C = C_W – C_E . . .(O.D)$

$C = C_W + C_E$

$C_w = 4 Iw .W_w.w_p$

$C_E = I_E . W_E . W_p$

$C = 4IW + W_w . w_p \pm I_E. W_E . W_p$

Gear ratio , $G = \frac{W_E}{W_w}$

$\therefore W_E = G \ W_w$

$C = 4 Iw . W_w . W_p \pm IE . G W_W . W_p$

$\therefore$ $C = W_w. W_p \ [4Iw \pm I_E . G]$