Brain Teasers and Puzzles 

Workings

Hint
Perhaps looking around the shapes will help.

Answer
C.

Reasoning
The shapes are the spaces between the digits in the numbers 27, 28, 29, and 30, therefore C is the correct answer, as it is the space between the digits in the number 31.

Workings

Hint
Look at the number of sides of each of the shapes.

Answer
Square.

Reasoning
If we add the shape's sides, the total increases by 8, then 10, then 12, etc (2 more each time).
   triangle (3) + pentagon (5) + square (4) = 12

   square   (4) + hexagon (6) + hexagon (6) + square (4) = 20

   pentagon (5) + hexagon (6) + hexagon (6) + hexagon (6) + square (4) + triangle (3) = 30

Therefore:
   hexagon  (6) + octagon (8) + octagon (8) + octagon (8) + octagon (8) + square (4) = 42

Alternative Reasoning
Square the first shape's sides, and the remaining shapes add up to this number.
   triangle (3 x 3) = pentagon (5) + square (4)

   square   (4 x 4) = hexagon (6) + hexagon (6) + square (4)

   pentagon (5 x 5) = hexagon (6) + hexagon (6) + hexagon (6) + square (4) + triangle (3)

Therefore:
   hexagon  (6 x 6) = octagon (8) + octagon (8) + octagon (8) + octagon (8) + square (4)

Workings

Hint
The words are all vegetables.

Answers
cbbg   = cabbage clflwr = cauliflower ccmbr  = cucumber crgtt  = courgette crrt   = carrot clrc   = celeriac

Workings

Hint
One of the words is GONE.

Answers
bo + nd = bond
br + ew = brew
fo + am = foam
go + ne = gone
ho + pe = hope
jo + ke = joke
le + af = leaf
lo + af = loaf
lo + ud = loud
so + re = sore

If we remove the restriction of remaking common words, alternative answers can be found using: foud, goaf, leud, sone.