16 women take 12 days to complete a work which can be completed by 12 men in 8 days. 16 men started working and after 3 days 10 men left and 4 women joined them. How many days will they take to complete the remaining work ?

$$\eqalign{ & 16{\text{ women}} \times {\text{12}} = {\text{12 men}} \times {\text{8}} \cr & {\text{2 women}} = {\text{1 man}} \cr & {\text{Total work}} \cr & = {\text{12 men}} \times {\text{8 days}} \cr & = {\text{96 units}} \cr & {\text{16 men do work in 3 days}} \cr & = 16 \times 3 \cr & = 48{\text{ units}} \cr & {\text{Work left }}96 - 48 = 48{\text{ units}} \cr} $$
16 men - 10 men left = 6 men + 4 women join
$$\eqalign{ & {\text{6men}} + {\text{2 men}} = {\text{8 men}} \cr & {\text{8 men will do 48 units in}} \cr & = \frac{{48}}{8} \cr & = 6{\text{ days}} \cr} $$