Puzzles - Missing letters puzzles

Answer

:

F

Explanation

:

Working in rows, from top to bottom, the sum of the numerical values of the letters in each row starts at 12, and increases by 2 as you go down each row.

Answer

:

G

Explanation

:

The numerical values of the letters in opposite segments of the circle add up to 16 each time.

Answer

:

H

Explanation

:

Working from top to bottom, letters are written in pairs. Take the 2 digit numerical value of the first letter and add the 2 digits together. Write the letter with this numerical value in the next space down. Continue in this way down the line.