R. It’s a representation of a stick shift, where 1-5 are gears and R represents reverse.

Add EL (one-third of TWELVE) to EVEN (four-fifths of SEVEN) and get ELEVEN.

K. It’s the series of capital letters without curves in alphabetical order.

Four daughters and three sons. Each daughter has 3 sisters and 3 brothers, and each brother has 2 brothers and 4 sisters.

To figure it out mathematically, you could use the following two equations where G = the number of girls and B = the number of boys:
G – 1 = B
2(B – 1) = G

Solving for G gives you 4 and plugging that in to G – 1 = B gives you a B of 3.

Milton was a forgetful and naughty fellow. He was summoning his courage to approach the counter to return his overdue book. The kindly lass at the counter saw the book was 15 days overdue and had accrued the egregious late fee of $3.75 (25 cents a day). Lesson learned, Milton never returned a book late again.

Cut #1 – Down the center of the cake (vertically) leaving two equal halves.
Cut #2 – Across the center of the cake (horizontally) leaving four equal slices.
Cut #3 – Through the middle edge of the cake slicing all four of the pieces in equal halves, leaving eight equal slices (four equal tops and four equal bottoms).

29%

To read more about this, see the False Positive Paradox page on Wikipedia.