Its 16.
So you have 12 miles on that trail, and markers every 2/3 of the way there. If you were to divide 2 with 3 then you can get the decimal of the fraction. Which in this case it’s 0.75. So every single 0.75 of the mile there is a marker. Divide 12 with 0.75 and you get 16 markers.
Hoped this helped in some way.
Choosing 4 men from seven can be done in 7C4 = 35 ways
(There are 7 to choose from then 6 and 5 and 4 = 7 x 6 x 5 x 4
but we don’t want them in order so we need to divide by 4! = 4 x 3 x 2 x 1)
Similarly choosing 4 women from 11 can be done in 11C4 = 330 ways.
Total number of ways to choose 4 men and 4 women = 35 x 330 = 11550
remember that when total value is used a negative number is turned positive so it equals to 282 feet