The Two Numbers Puzzles
Either Horizontal Pairs add up to the same number
For example 50+6=56, 17+39=56, 30+26=56, 15+ ??? = 56, so 41 is the right answer.
Or Vertical Pairs add up to consecutive numbers
For example 46+21=67
so 22 would be right answer
The Two Sculptures Puzzles
If Emperor statues both sides at each mile
In this case 3 for the beginning mile (2 for either end, and one large), 160 for the ones on either side of miles 1 through 80, and 40 large monuments for mile 1 through 80, for a total of 179
If an Emperor Statue each mile
the idea is you have 70 small states and 70/5 monuments, then add one more statue and one more monument for mile zero, so the guess would be 70+70/5+2=86
How many at the Ball?
If there were one Prince, there would be 5 Duchesses and 10 Marquises for a total of 16. Since 6 times 16 is 96, there are 6 Princes!
The acres from your subject are already in counted in your total, so 23+8-3+5=33
Below is a Google search which can be handy. Try "4 miles in fathoms"