The places of the letters F and N in the English alphabet are added together. Which letter stands at the place given by that total?

F stands at place 6 and N at place 14, so the total is 20, and the twentieth letter is T. Counting F as 5 or N as 13, as happens when the alphabet is counted from zero, gives 19, which is S; counting one of them one place too far gives 21, which is U; taking both a place short gives 18, which is R.