Puzzles - Missing letters puzzles

Exercise : Missing letters puzzles
148.
Answer
:
Y
Explanation
:
Starting with the bottom left letter and moving in a clockwise spiral towards the centre, letters advance through the alphabet in steps of 4, 5, 6 etc.

149.
Answer
:
E
Explanation
:
Starting with the bottom row and moving up, one row at a time, the sum of the numerical values of the letters starts at 26 for the bottom row, then 24, 22 and 20 as you move up.

150.
Answer
:
X
Explanation
:
Starting with the bottom right hand corner, and moving in a clockwise spiral towards the centre, letters advance through the alphabet, skipping 4 letters at a time.