Hi there! 1)It's a very common problem for me . I don't get when do I have to multiply or divide a fraction in unitary method e.g. 10 men do 1 work in 40 days 10 men does 3/4 work in 40*3/4 days or should i do 10 men does 3/4 work in 40*4/3 days I do't undestand!Plz give me a reason why should I multiply or divide it. I would be very grateful if anybody does so! 2)The problem: Forty men finish a piece of work in 40 days; if % men leave the work every ten days,in what time will the whole work be completed. My try: I tried to put it like this 40 men in 40 days does 1 work 40 men in 1 day does 1/40 work 40 men in 10 day does 1/40 *10work=1/4 But if I do so I becomes a very very long method. Isn't there any shorter way. Please help! Thank you.