RE: Puzzle Contest #12 - First to get all the correct answers wins 5 SBD, all attempts will receive an upvote.

[bolanlebolaji]

Thanks @spectrumecons for this contest.
You made the maths-genius in me come alive.
My answers are :

Answer 1a, 23, 1b, 7 1c, 18
Answer 2a, 24 2b, 54 2c, 9
Answer 3, E
Answer 4a, -5 4b, 4