An exterior architect is asked by a builder to plant seven trees in a manner that there are exactly six rows of trees in a straight line and each row has three trees in particular.

How will he do it?

If 17 men and 18 women can do a piece of work in 11 days and 14 men and 13 women can do it in 15 days. How many days will 27 men and 18 women take to do it?

If 10 men and 15 women can do a piece of work in 8 days and 9 men and 12 women can do it in 9 days. How many days will 5 men and 15 women take to do it?

If 11 men and 16 women can do a piece of work in 6 days and 7 men and 9 women can do it in 10 days. How many days will 15 women and 5 men take to do it?

If 6 men and 10 women can do a piece of work in 15 days and 5 men and 9 women can do it in 17 days. How many days will 5 men and 12 women take to do it?

If 6 men and 8 women can do a piece of work in 10 days and 4 men and 7 women can do it in 12 days, how many days will 4 men and 12 women take to do half of work?