4 men and 6 women can complete a work in 8 days, while 3 men and 7 women can complete it in 10 days. In how many days will 10 women complete it?

Let 1 man's 1 day's work = x and 1 woman's 1 day's work = y
Then, 4x + 6y = $$\frac{1}{8}$$ and 3x + 7y = $$\frac{1}{{10}}$$
Solving the two equations, we get
$$x = \frac{{11}}{{400}},\,\,\,y = \frac{1}{{400}}$$
∴ 1 woman's 1 day's work = $$\frac{1}{{400}}$$
⇒ 10 women's 1 day's work = $$ {\frac{1}{{400}} \times 10} $$   = $$\frac{1}{{40}}$$
Hence, 10 women will complete the work in 40 days